feat: add remote device settings portal and Pi hot reload

- add /settings/device portal page and portal device-config GET endpoint
- add portal navigation and client-side device settings editor UI
- hot-reload Account/Car display config after local saves and server syncs
- document portal workflow and Phase 25.5b completion
- add runtime reload tests for account, car, and sync callback

Co-authored-by: Copilot <[email protected]>

PLAN.md

@@ -1532,11 +1532,32 @@ phase roadmap.
   service restarted cleanly, and unraid rebuilt the API stack after manually applying
   `migrate_phase25_5a.sql`.
 
-#### Next phase (Phase 25.5b)
-- Hot-reload handler to apply config changes without restart
-- Server portal UI for editing device config (admin page)
-- Device settings page on portal to test config updates
-- Mobile-friendly device management UI
+### Phase 25.5b: Remote portal device settings + hot-reload — ✅ COMPLETE
+**The remote editor and Pi-side hot-reload are now wired.** The server portal can
+edit the device identity that the Pi sync thread consumes, and the running Pi UI
+updates its display-facing values without a manual restart once sync lands.
+
+#### Implemented (Phase 25.5b so far)
+- **Remote portal page**: `/settings/device` renders a login-protected editor for
+  `owner_name`, `car_model`, `device_name`, and `avatar_path`
+- **Portal JSON endpoint**: `GET /api/v1/portal/device-config` returns the current
+  config for the configured single-device deployment
+- **Navigation**: desktop sidebar + mobile bottom nav now expose **Device settings**
+- **Portal UX**: live avatar preview, config-version display, dirty-state save
+  button, and inline sync/explanation text
+- **Pi hot-reload**:
+  - `Account.reload_runtime_config()` and `Car.reload_runtime_config()` refresh
+    display fields from the live SQLite-backed device config
+  - local `/api/device-config` saves now reload the in-process `account`/`car`
+    objects immediately
+  - server sync now invokes a registered reload callback after writing new config
+    locally, so next-page renders reflect synced values without restarting Flask
+
+#### Validation
+- Added runtime reload tests for `Account`, `Car`, and the sync callback path
+- Existing suite still passes (`66 passed`)
+- Remote deployment / live portal-path verification still recommended whenever the
+  server portal is updated
 
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