v0.3.0: local free check-in with actionable countdown notification (Phase C)

For a zone labeled free_2h/3h/4h, "Check in (free · Xh)" starts a local, API-free
countdown to the free limit — no ParkSmarter call. The bbp-notify module gains a
showCheckin() that posts the ticking chronometer with "End" / "Pay" buttons, a
BbpActionReceiver (declared in the module's new AndroidManifest.xml) that records
the tap in SharedPreferences and, for Pay, relaunches the app; consumePendingAction()
is drained on foreground by useCheckinSync() — End clears the check-in, Pay hands
off to StartSession for the stored zone. A pre-expiry alert reuses the existing
reminder lead-minutes. Starting a paid session supersedes an active check-in.

Also: MeterDetail shows the free/pay-immediate label and (admins) labeling chips.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/modules/bbp-notify/android/src/main/AndroidManifest.xml

@@ -0,0 +1,9 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+  <application>
+    <!-- Fully-qualified name: relative ".Name" would resolve against the app
+         package, not this module's namespace, once manifests are merged. -->
+    <receiver
+      android:name="expo.modules.bbpnotify.BbpActionReceiver"
+      android:exported="false" />
+  </application>
+</manifest>