Android 2.6.5: Adreno Vulkan default, low-latency default, UI sounds, RA client hardening, GameDB

Rendering
- Auto renderer now resolves to Vulkan HW on Adreno (OpenGL elsewhere).
- Mobile hardware ROV (Phase 0): tile-native depth feedback behind the ROV toggle.

Performance & input
- Low Latency frame pacing is the default on capable devices, with a one-time
  migration for existing installs; low-end devices keep the queued pacing.
- Reduce Android input latency and improve input handling (PR #403, Splaser).
- Experimental CPU clock hint (ADPF) toggle in Performance settings (default off).

Audio & UI
- Pop-up open/close sound cues (info, hardcore confirm, patches & cheats).
- Alternating controller navigation / slider tick sounds.

RetroAchievements
- Inject the RA client version from a build-time secret kept out of public source,
  with a stock-PCSX2 fallback (no hardcore) for secret-less builds. Applies to the
  iOS client token too. Prevents third parties from copying our User-Agent.

Game compatibility
- Delta Force: Black Hawk Down (SLUS-21124 / SLES-53299) GameDB fixes
  (PR #401, XDarkFallenX).

.gitignore

@@ -147,3 +147,7 @@ CMakeSettings.json
 
 # Achievement sounds are shipped assets, not build output — keep them tracked
 !platforms/android/app/src/main/assets/resources/sounds/**/*.wav
+
+# RetroAchievements client User-Agent secret — the real pinned version is injected
+# from this header at build time and must NEVER be committed (spoofing prevention).
+ra_ua_secret.h