fix(docker): update Dockerfile and CI for monorepo workspace structure

Dockerfile:
- Add shared-builder stage that produces @trek/shared dist before
  client and server stages need it
- Each build stage carries root package.json + package-lock.json so npm
  can resolve @trek/shared as a workspace dependency
- Production stage installs via workspace context (npm ci --workspace=server
  --omit=dev) so node_modules/@trek/shared symlinks to shared/dist correctly
- Copy server/tsconfig.json into the image so tsconfig-paths/register can
  find the MCP SDK path aliases at runtime
- CMD cds into /app/server before starting node so tsconfig-paths baseUrl
  resolves and ../node_modules points to /app/node_modules
- Remove mkdir for /app/server (now a real dir); keep symlinks for uploads/data

docker.yml version-bump:
- Replace manual per-workspace cd+npm-version calls with single:
  npm version --workspaces --include-workspace-root --no-git-tag-version
  (mirrors the version:* scripts in root package.json)
- git add now references root package-lock.json; adds shared/package.json

.dockerignore: add shared/dist
package.json: fix version:prerelease preid (alpha → pre)

.dockerignore

@@ -2,6 +2,7 @@ node_modules
 client/node_modules
 server/node_modules
 client/dist
+shared/dist
 data
 uploads
 .git