security: internal audit — batch 1

Fixes the critical + high + medium findings from our internal security
review. Bundled into one PR because the changes overlap heavily (JWT
verification unifies across three call sites; backup-code hashing and
demo-email handling cross-cut several services); splitting them out
would mean redundant reviews of the same files.

Critical
- CI-C1 — .github/workflows/test.yml: restore actions/{checkout,setup-
  node,upload-artifact} to @v4. The @v6 refs don't exist, so the test
  workflow was errorring before a single test ran.
- SEC-C1 — mfaPolicy now extracts the token via extractToken() (cookie-
  first, Bearer fallback). Previously it only read Authorization, so
  every cookie-authenticated SPA session bypassed require_mfa entirely.
- SEC-C2/C4/C6 — all JWT verification paths (MCP bearer, file download,
  photo route) now go through the shared verifyJwtAndLoadUser that
  checks password_version. resetPassword additionally deletes every
  mcp_tokens row and marks outstanding oauth_tokens revoked, so a
  password reset invalidates ALL credential classes — not just the
  cookie JWT.

High
- SEC-H2 — reset email URL is built from server-side APP_URL /
  ALLOWED_ORIGINS (via existing getAppUrl()), not request headers.
  Closes the host-header-injection vector into reset links.
- SEC-H3 — OIDC findOrCreateUser wraps the invite-redemption UPDATE +
  user INSERT in a transaction. The UPDATE is the capacity check; if
  a concurrent callback takes the last slot, the whole transaction
  aborts with registration_disabled instead of double-creating users.
- SEC-H4 — new verifyIdToken() performs full JWT signature
  verification via the provider's JWKS (Node's crypto.createPublicKey
  accepts JWK directly — no extra dependency), plus iss/aud/exp
  checks. The callback also rejects the login when userinfo.sub does
  not match id_token.sub.
- SEC-H5 — OAuth DCR now validates redirect_uris against an allowlist
  of schemes: https, http-loopback, or a private custom scheme. Plain
  http://non-loopback is rejected.
- SEC-H6 — oauthService audience defaults to mcpResource when the
  `resource` parameter is missing, so tokens are always audience-bound
  to /mcp instead of being issued with audience=null.
- SEC-H7 — HSTS is enabled any time NODE_ENV=production (previously
  required FORCE_HTTPS=true), includeSubDomains defaults on and can
  be disabled with HSTS_INCLUDE_SUBDOMAINS=false.
- SEC-H8 — trek_session cookie Secure flag is also driven by
  req.secure (which Express resolves from X-Forwarded-Proto once
  trust proxy is set), so instances behind a TLS-terminating proxy
  get Secure cookies without needing FORCE_HTTPS.

Medium
- SEC-M1 — permanentDeleteFile / emptyTrash / avatar unlink now use
  fs.promises.rm with { force: true } (one async op vs the previous
  existsSync + unlinkSync pair per file).
- SEC-M2 — invalidatePermissionsCache() is called inside restoreFromZip
  so a restored DB with different permission rows is honoured
  immediately.
- SEC-M3 + C1 — idempotency store bounds the key at 128 chars, caches
  only responses ≤ 256 KiB, and scopes the lookup by (key, user_id,
  method, path) rather than (key, user_id). Same key replayed against
  a different endpoint no longer returns a stale unrelated body.
- SEC-M4 — share_tokens gets an expires_at column; new tokens default
  to 90-day TTL, expired tokens are denied at lookup. Existing tokens
  stay NULL = no expiry so already-published links don't break.
- SEC-M5 — /uploads/photos/:filename now resolves the photo to its
  trip_id and requires the share token to cover THAT trip. Previously
  any share token for any trip would unlock any photo filename.
- SEC-M6 — BLOCKED_EXTENSIONS is the single source of truth shared
  between fileService and collab uploads. The '*' allowed_file_types
  wildcard now still rejects executables/scripts.
- SEC-M7 — single DEMO_EMAILS constant (services/demo.ts) used by
  demoUploadBlock, mfaPolicy, and every demo-mode guard in
  authService. The old demoUploadBlock only matched 'demo@nomad.app'
  so the seed 'demo@trek.app' could in fact upload in demo mode.
- SEC-M8 — MFA backup codes are now bcrypt-hashed at rest
  (hashBackupCodeBcrypt). matchBackupCode accepts both bcrypt and
  legacy SHA-256 hex hashes, so existing installs keep working until
  the user regenerates codes via enableMfa.
- SEC-M9 — document the "security via UUID v4 filename" model for
  /uploads/avatars|covers|journey. Requires no code change but
  captures the decision so future reviewers don't re-flag it.
- SEC-M10 — already covered by the resetPassword revocation logic
  above: mcp_tokens DELETE + oauth_tokens UPDATE … SET revoked_at.

Performance
- PERF-H1 — new migration adds the indexes flagged in the audit:
  trips(user_id), trips(created_at DESC), photos(day_id),
  photos(place_id), reservations(day_id), share_tokens(token), plus
  conditional day_accommodations and notifications indexes depending
  on which columns are present.

Tests
- tests/integration/oidc.test.ts now mocks verifyIdToken and passes
  an id_token in the exchangeCodeForToken stub for the three flows
  that exercise a successful callback. The three remaining failures
  tests pointed out were all pre-existing (file-upload flakes +
  notificationPreferences event_types count drift), none introduced
  by this PR.

server/src/routes/auth.ts

@@ -39,7 +39,7 @@ import {
   requestPasswordReset,
   resetPassword,
 } from '../services/authService';
-import { sendPasswordResetEmail } from '../services/notifications';
+import { sendPasswordResetEmail, getAppUrl } from '../services/notifications';
 
 const router = express.Router();
 
@@ -127,10 +127,10 @@ router.get('/app-config', optionalAuth, (req: Request, res: Response) => {
   res.json(getAppConfig(user));
 });
 
-router.post('/demo-login', (_req: Request, res: Response) => {
+router.post('/demo-login', (req: Request, res: Response) => {
   const result = demoLogin();
   if (result.error) return res.status(result.status!).json({ error: result.error });
-  setAuthCookie(res, result.token!);
+  setAuthCookie(res, result.token!, req);
   res.json({ token: result.token, user: result.user });
 });
 
@@ -144,7 +144,7 @@ router.post('/register', authLimiter, (req: Request, res: Response) => {
   const result = registerUser(req.body);
   if (result.error) return res.status(result.status!).json({ error: result.error });
   writeAudit({ userId: result.auditUserId!, action: 'user.register', ip: getClientIp(req), details: result.auditDetails });
-  setAuthCookie(res, result.token!);
+  setAuthCookie(res, result.token!, req);
   res.status(201).json({ token: result.token, user: result.user });
 });
 
@@ -155,7 +155,7 @@ router.post('/login', authLimiter, (req: Request, res: Response) => {
   }
   if (result.error) return res.status(result.status!).json({ error: result.error });
   if (result.mfa_required) return res.json({ mfa_required: true, mfa_token: result.mfa_token });
-  setAuthCookie(res, result.token!);
+  setAuthCookie(res, result.token!, req);
   res.json({ token: result.token, user: result.user });
 });
 
@@ -178,11 +178,12 @@ router.post('/forgot-password', forgotLimiter, async (req: Request, res: Respons
   const outcome = requestPasswordReset(rawEmail, ip);
 
   if (outcome.reason === 'issued' && outcome.tokenForDelivery && outcome.userEmail) {
-    // Build the reset URL from the incoming request origin so dev /
-    // prod both work without extra config.
-    const origin = (req.headers['origin'] as string | undefined)
-      || (req.headers['referer'] ? new URL(req.headers['referer'] as string).origin : undefined)
-      || `${req.protocol}://${req.get('host')}`;
+    // Build the reset URL from the server-side canonical APP_URL (or
+    // first ALLOWED_ORIGINS entry) — never from request headers. A
+    // crafted `Origin` / `Host` / `Referer` would otherwise put an
+    // attacker-controlled domain into the emailed reset link while the
+    // token itself is still legitimate.
+    const origin = getAppUrl();
     const url = `${origin.replace(/\/$/, '')}/reset-password?token=${encodeURIComponent(outcome.tokenForDelivery)}`;
 
     // Audit the REQUEST always — even for "no user" — so abuse is visible.
@@ -231,8 +232,8 @@ router.get('/me', authenticate, (req: Request, res: Response) => {
   res.json({ user });
 });
 
-router.post('/logout', (_req: Request, res: Response) => {
-  clearAuthCookie(res);
+router.post('/logout', (req: Request, res: Response) => {
+  clearAuthCookie(res, req);
   res.json({ success: true });
 });
 
@@ -276,15 +277,15 @@ router.get('/me/settings', authenticate, (req: Request, res: Response) => {
   res.json({ settings: result.settings });
 });
 
-router.post('/avatar', authenticate, demoUploadBlock, avatarUpload.single('avatar'), (req: Request, res: Response) => {
+router.post('/avatar', authenticate, demoUploadBlock, avatarUpload.single('avatar'), async (req: Request, res: Response) => {
   const authReq = req as AuthRequest;
   if (!req.file) return res.status(400).json({ error: 'No image uploaded' });
-  res.json(saveAvatar(authReq.user.id, req.file.filename));
+  res.json(await saveAvatar(authReq.user.id, req.file.filename));
 });
 
-router.delete('/avatar', authenticate, (req: Request, res: Response) => {
+router.delete('/avatar', authenticate, async (req: Request, res: Response) => {
   const authReq = req as AuthRequest;
-  res.json(deleteAvatar(authReq.user.id));
+  res.json(await deleteAvatar(authReq.user.id));
 });
 
 router.get('/users', authenticate, (req: Request, res: Response) => {
@@ -329,7 +330,7 @@ router.post('/mfa/verify-login', mfaLimiter, (req: Request, res: Response) => {
   const result = verifyMfaLogin(req.body);
   if (result.error) return res.status(result.status!).json({ error: result.error });
   writeAudit({ userId: result.auditUserId!, action: 'user.login', ip: getClientIp(req), details: { mfa: true } });
-  setAuthCookie(res, result.token!);
+  setAuthCookie(res, result.token!, req);
   res.json({ token: result.token, user: result.user });
 });