feat(android): HDR (Main10 / BT.2020 PQ) + fix ndk feature gating

Mirrors the Apple client's HDR path so the Android client can display HDR from a
Windows HDR host:
- nativeConnect now advertises VIDEO_CAP_10BIT | VIDEO_CAP_HDR (was 0), so the
  host upgrades to a Main10 / BT.2020 PQ encode.
- decode.rs detects HDR reactively from the decoder's reported output colour
  (color-transfer ST2084=6 / HLG=7, color-range) -- the AMediaCodec analogue of
  VideoToolbox's format description on Apple -- and signals the Surface dataspace
  (Bt2020[Itu]Pq / Bt2020[Itu]Hlg) so the compositor/display switch to HDR.
  AMediaCodec decodes Main10 from the in-band SPS; no profile override needed.

Also fixes the Android build: set_frame_rate (added in e9de730) is gated on the
ndk `nativewindow` + `api-level-30` features, which weren't enabled -- so that
commit could not compile under cargo-ndk. Enable
features = ["media","audio","nativewindow","api-level-31"] (minSdk 31): covers
set_frame_rate (api-30), set_buffers_data_space + the DataSpace module (api-28),
and ANativeWindow (nativewindow).

Verified host-side: fmt --all + clippy --workspace (the caps advertise + JNI
surface). The android-gated decode + NDK gating verified against the ndk 0.9
sources; android.yml (cargo-ndk) is the compile gate, and real HDR display needs
an HDR device + Windows HDR host.

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

clients/android/native/src/session.rs

@@ -184,10 +184,13 @@ pub extern "system" fn Java_io_unom_punktfunk_kit_NativeBridge_nativeConnect<'lo
         CompositorPref::from_u8(compositor_pref.clamp(0, u8::MAX as jint) as u8),
         GamepadPref::from_u8(gamepad_pref.clamp(0, u8::MAX as jint) as u8),
         bitrate_kbps.max(0) as u32, // 0 = host default
-        0,                          // video_caps: 8-bit only on Android for now
-        None,                       // launch: default app
-        pin,                        // Some → Crypto on host-fp mismatch
-        identity,                   // owned (cert, key) PEM, or None (anonymous)
+        // Advertise 10-bit + HDR: the host (e.g. Windows) only upgrades to a Main10 / BT.2020 PQ
+        // encode when the client sets these. AMediaCodec decodes Main10 from the SPS and the decode
+        // loop signals the Surface's HDR dataspace from the reported colour (see crate::decode).
+        punktfunk_core::quic::VIDEO_CAP_10BIT | punktfunk_core::quic::VIDEO_CAP_HDR,
+        None,     // launch: default app
+        pin,      // Some → Crypto on host-fp mismatch
+        identity, // owned (cert, key) PEM, or None (anonymous)
         Duration::from_secs(10),
     ) {
         Ok(client) => {