test: expand test suite to 87.3% backend coverage

Add new integration test files covering previously untested routes:
- categories.test.ts — GET /api/categories
- oidc.test.ts — full OIDC login flow (callback, state, errors)
- settings.test.ts — GET/PUT /api/settings, bulk save
- tags.test.ts — CRUD for trip tags
- todo.test.ts — todo items CRUD and reorder

Add new unit test files covering service-layer logic:
- adminService.test.ts — user/invite management, packing templates, OIDC settings
- atlasService.test.ts — atlas search and place enrichment
- authServiceDb.test.ts — DB-backed auth helpers (login, register, MFA)
- backupService.test.ts — export/import/restore logic
- categoryService.test.ts — category CRUD
- dayService.test.ts — day management and accommodation helpers
- mapsService.test.ts — route/directions helpers
- oidcService.test.ts — OIDC state, auth code, role resolution, user upsert
- packingService.test.ts — packing item/bag/template operations
- placeService.test.ts — place CRUD and tag attachment
- settingsService.test.ts — settings get/set/bulk
- tagService.test.ts — tag CRUD
- todoService.test.ts — todo CRUD and reorder
- tripService.test.ts — trip CRUD, member management, archiving
- vacayService.test.ts — vacay integration helpers
- tripAccess.test.ts (middleware) — requireTripAccess middleware

Expand existing integration and unit test files with additional cases
across admin, atlas, auth, backup, collab, days, files, maps, memories
(Immich/Synology), notifications, places, reservations, share, vacay,
weather, auth middleware, ephemeral tokens, notification preferences,
permissions, SSRF guard, and WebSocket connection tests.

Update test helpers (factories.ts, test-db.ts) with new factory
functions and seed data required by the expanded suite.

Fix minor issues in server/src/routes/reservations.ts and
server/src/services/atlasService.ts surfaced by new test coverage.

Update sonar-project.properties to reflect new coverage thresholds.

server/src/routes/reservations.ts

@@ -13,6 +13,7 @@ import {
   updateReservation,
   deleteReservation,
 } from '../services/reservationService';
+import { createBudgetItem, updateBudgetItem, deleteBudgetItem } from '../services/budgetService';
 
 const router = express.Router({ mergeParams: true });
 
@@ -53,7 +54,6 @@ router.post('/', authenticate, (req: Request, res: Response) => {
   // Auto-create budget entry if price was provided
   if (create_budget_entry && create_budget_entry.total_price > 0) {
     try {
-      const { createBudgetItem } = require('../services/budgetService');
       const budgetItem = createBudgetItem(tripId, {
         name: title,
         category: create_budget_entry.category || type || 'Other',
@@ -126,7 +126,6 @@ router.put('/:id', authenticate, (req: Request, res: Response) => {
   if (!create_budget_entry || !create_budget_entry.total_price) {
     const linked = db.prepare('SELECT id FROM budget_items WHERE trip_id = ? AND reservation_id = ?').get(tripId, id) as { id: number } | undefined;
     if (linked) {
-      const { deleteBudgetItem } = require('../services/budgetService');
       deleteBudgetItem(linked.id, tripId);
       broadcast(tripId, 'budget:deleted', { id: linked.id }, req.headers['x-socket-id'] as string);
     }
@@ -135,7 +134,6 @@ router.put('/:id', authenticate, (req: Request, res: Response) => {
   // Auto-create or update budget entry if price was provided
   if (create_budget_entry && create_budget_entry.total_price > 0) {
     try {
-      const { createBudgetItem, updateBudgetItem } = require('../services/budgetService');
       const itemName = title || current.title;
       const existing = db.prepare('SELECT id FROM budget_items WHERE trip_id = ? AND reservation_id = ?').get(tripId, id) as { id: number } | undefined;
       if (existing) {

server/src/services/atlasService.ts

@@ -241,7 +241,7 @@ export async function getStats(userId: number) {
 
   const countries = [...countrySet.values()].map(c => {
     const countryTrips = trips.filter(t => c.tripIds.has(t.id));
-    const dates = countryTrips.map(t => t.start_date).filter(Boolean).sort();
+    const dates = countryTrips.map(t => t.start_date).filter(Boolean).sort((a, b) => a.localeCompare(b));
     return {
       code: c.code,
       placeCount: c.places.length,
@@ -272,7 +272,7 @@ export async function getStats(userId: number) {
     }
   }
 
-  const mostVisited = countries.length > 0 ? countries.reduce((a, b) => a.placeCount > b.placeCount ? a : b) : null;
+  const mostVisited = countries.length > 0 ? countries.reduce((a, b) => a.placeCount > b.placeCount ? a : b, countries[0]) : null;
 
   const continents: Record<string, number> = {};
   countries.forEach(c => {