feat(client/android): Snapdragon latency tuning — ADPF pipeline hints, game mode, max-clock decode

Three levers to lower and steady decode latency on Snapdragon (Adreno) devices:

- ADPF (Adaptive Performance Framework): a new dlsym-resolved hint session
  (native/src/adpf.rs; API-33+, resolved at runtime so there's no build-time
  link dependency and libpunktfunk_android.so still loads on API 31/32) tells
  the CPU governor the video pipeline runs a per-frame real-time workload, so it
  keeps those threads on fast cores at high clocks. It now covers all three
  latency-critical threads — the pf-decode feed/drain/present loop, the core
  data-plane pump (UDP receive + FEC reassembly), and the audio thread — via a
  new generic hot-thread registry on NativeClient (register_hot_thread /
  hot_thread_ids; the pump self-registers). The session is built lazily on the
  first presented frame, since ADPF createSession rejects a set containing any
  not-yet-live tid.

- operating-rate -> Short.MAX ("as fast as possible"): pushes the Qualcomm
  decoder to run each frame at max clocks instead of merely sustaining the
  display rate at a power-saving clock that adds per-frame decode latency.

- appCategory="game": makes the app eligible for OEM Game Mode / Game Dashboard
  performance profiles.

The core registry is cross-platform (gettid on Linux/Android, a no-op
elsewhere) — no Android-specific pollution of the shared core. Host workspace +
64 core tests green; Android arm64-v8a + x86_64 (platform 31) build + clippy
clean. On-device Snapdragon validation pending.

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

clients/android/app/src/main/AndroidManifest.xml

@@ -27,8 +27,15 @@
     <uses-feature android:name="android.software.leanback" android:required="false" />
     <uses-feature android:name="android.hardware.gamepad" android:required="false" />
 
+    <!-- appCategory="game": a game-streaming client IS a game as far as the SoC is concerned.
+         On Snapdragon devices (and other OEMs with a Game Mode / Game Dashboard) this makes the app
+         eligible for the vendor's game performance profile — the aggressive CPU/GPU governor and
+         scheduler treatment games get — which, together with the ADPF hints in the native decode
+         path, is what keeps clocks up for low, consistent decode latency. Also groups it correctly
+         under Games in battery/data usage. Advisory: devices without Game Mode ignore it. -->
     <application
         android:allowBackup="false"
+        android:appCategory="game"
         android:icon="@mipmap/ic_launcher"
         android:roundIcon="@mipmap/ic_launcher_round"
         android:label="@string/app_name"