refactor(android): split session JNI into modules, HUD-gated stats, AAudio open retry

- native: the 756-line session.rs becomes session/{mod,connect,input,planes}.rs
  around a SessionHandle (connect lifecycle + trust, input plane shims, plane
  start/stop + stats drain).
- Decode-stats sampling is HUD-gated (nativeSetVideoStatsEnabled): with the
  overlay hidden the decode thread skips the per-AU clock read + lock; enabling
  resets the measurement window.
- audio: the AAudio open path is a per-sharing-mode try_open closure — the
  realtime callback state (ring, prime, free-list) is rebuilt per attempt, so a
  failed exclusive-mode try can't leak state into the shared-mode retry.
- Kotlin: ConnectScreen/StreamScreen slimmed by extracting ConnectDialogs,
  StatsOverlay and TouchInput.

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

clients/android/native/src/lib.rs

@@ -16,10 +16,10 @@
 //! Wi-Fi `MulticastLock` + permission UX, Keystore identity).
 //!
 //! JNI symbols map to `io.unom.punktfunk.kit.NativeBridge` in the `:kit` Gradle module
-//! (`clients/android`). The current surface is the scaffold's native-link proof
-//! (`abiVersion`/`coreVersion`) plus the session handle lifecycle in [`session`]; the per-plane
-//! pumps (video → AMediaCodec, audio → Oboe), input, audio, pairing and mode renegotiation are
-//! the next milestone (see the TODOs in [`session`]).
+//! (`clients/android`). The surface: the native-link proof (`abiVersion`/`coreVersion`), mDNS host
+//! discovery ([`discovery`]), and the session lifecycle in [`session`] — connect/pair + the trust
+//! surface, the per-plane pumps (video → AMediaCodec, audio ↔ AAudio, mic uplink), input, and
+//! rumble/HID feedback ([`feedback`]). Mode renegotiation is still TODO (see [`session`]).
 
 use jni::objects::JObject;
 use jni::sys::jint;