Reservation end time, route perf overhaul, assignment search fix

- Add reservation_end_time field (DB migration, API, UI)
- Split reservation form: separate date, start time, end time, status fields
- Fix DateTimePicker forcing 00:00 when no time selected
- Show end time across all reservation displays
- Link-to-assignment and date on same row (50/50 layout)
- Assignment search now shows day headers for filtered results
- Auto-fill date when selecting a day assignment
- Route segments: single OSRM request instead of N separate calls (~6s → ~1s)
- Route labels visible from zoom level 12 (was 16)
- Fix stale route labels after place deletion (useEffect triggers recalc)
- AbortController cancels outdated route calculations

server/package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "nomad-server",
-  "version": "2.5.5",
+  "version": "2.6.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "nomad-server",
-      "version": "2.5.5",
+      "version": "2.6.0",
       "dependencies": {
         "archiver": "^6.0.1",
         "bcryptjs": "^2.4.3",