v0.2.3: true ticking countdown via a tiny native module (no deps)

Replaces the static status notification with a native Android chronometer that
counts DOWN to the session end — the system ticks it every second with zero app
CPU/battery, visible without opening the app.

- modules/bbp-notify: a ~50-line local Expo module using only NotificationCompat
  (setWhen + setUsesChronometer + setChronometerCountDown + ongoing). Zero
  third-party dependencies, no Firebase — fits the de-Googled ethos. Verified:
  autolinks + Kotlin compiles.
- sessionStatus.ts uses it when present, else falls back to the expo-notifications
  static expiry-time notification.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app/app.json

@@ -3,14 +3,14 @@
     "name": "BigBrainParking",
     "slug": "bigbrainparking",
     "scheme": "bigbrainparking",
-    "version": "0.2.2",
+    "version": "0.2.3",
     "orientation": "portrait",
     "userInterfaceStyle": "automatic",
     "newArchEnabled": true,
     "icon": "./assets/icon.png",
     "android": {
       "package": "top.mowden.bigbrainparking",
-      "versionCode": 12,
+      "versionCode": 13,
       "edgeToEdgeEnabled": true,
       "adaptiveIcon": {
         "foregroundImage": "./assets/adaptive-icon.png",