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]>

server/app.py

@@ -1,6 +1,6 @@
 """yaris-obd remote server: receives trip/GPS log batches and dashcam files
 uploaded by the Pi, storing them in Postgres + on-disk file storage.
-Also serves a read-only web portal for browsing trip history and dashcam archive.
+Also serves the remote web portal for browsing and managing the configured car.
 """
 import functools
 import hashlib
@@ -414,6 +414,15 @@ def portal_dashcam():
     return render_template("dashcam.html")
 
 
+@app.get("/settings/device")
+@require_login
+def portal_device_settings_page():
+    return render_template(
+        "device_settings.html",
+        configured_device_name=os.environ.get("DEVICE_NAME", "yaris-2013"),
+    )
+
+
 # ── Portal JSON API ────────────────────────────────────────────────────────
 
 @app.get("/api/v1/portal/stats")
@@ -621,6 +630,22 @@ def portal_trip_compat(trip_id):
 
 # ── Phase 25.5a: Device configuration sync ──────────────────────────────────
 
+@app.get("/api/v1/portal/device-config")
+@require_login
+def portal_device_config_get():
+    """Get the configured device identity for the remote portal."""
+    device_id = _portal_device_id()
+    if device_id is None:
+        return jsonify(error="device not configured"), 404
+
+    config = device_config.get_device_config(device_id)
+    if not config:
+        return jsonify(error="device not found"), 404
+
+    config["configured_device_name"] = os.environ.get("DEVICE_NAME", "yaris-2013")
+    return jsonify(config)
+
+
 @app.get("/api/device-config")
 @require_device_auth
 def api_device_config_get():