fix[notask]: ship Parakeet CPU-only on Android to stop Adreno Vulkan SIGABRT

[Zbig9000]

🎯 What problem does this PR solve?

• With the tts-ggml bootstrap crash fixed (revert: "QVAC-19255 tts-ggml: enable Supertonic GPU via tts-cpp 2026-06-05 (#2473)" #2502), the Android e2e now boots — but crashes on the first Parakeet test (parakeet-tdt-wav), killing the consumer and failing the whole batch ("All consumers are dead"). Android-only.
• Confirmed on device-farm runs 27282459468 (PR QVAC-20451 fix[skiplog]: stabilize Android logging reload e2e #2479) and 27286841825 (19-test parakeet-only run), Samsung S25 Ultra: SIGABRT on the mqt_v_js worklet ~8 s into loading parakeet-tdt-0.6b-v3, with the backtrace entirely inside libqvac__transcription-parakeet.0.7.1.so and the crash immediately preceded by AdrenoVK-0: Application Name: ggml-vulkan.

📝 How does it solve it?

Root cause: ParakeetModel::load already forces useGPU=false on Android (n_gpu_layers=0) "pending Vulkan/Mali and OpenCL/Adreno driver fixes" — but the addon still ships the libqvac-speech-ggml-{vulkan,opencl}.so backends, and parakeet-cpp's ggml_backend_load_all_from_path() initialises the Adreno Vulkan device regardless of n_gpu_layers. Once parakeet-cpp 2026-06-04#0 (#2461) added robust Adreno-generation detection, that init engages the Adreno Vulkan backend on the S25 Ultra and aborts in ggml.

Evidence it's a dependency regression (not the addon code): the same transcription-parakeet@0.7.1 passed Parakeet 4/4 on Android on Jun 5 (run 27030121365) — that build used the older parakeet-cpp 2026-05-26#2, which didn't detect the Adreno and stayed on CPU.

Fix: drop the vulkan/opencl vcpkg features from the Android parakeet-cpp dependency, so the Android prebuild is CPU-only — no GPU backend .so is shipped, so nothing initialises the Adreno driver. This completes the existing engine-boundary GPU-disable policy. iOS (Metal) and desktop (Vulkan) are unchanged. Version 0.7.1 → 0.7.2 (SDK pins ^0.7.1, so it picks this up).

This is the same class of Android Adreno-GPU ggml instability as the tts-ggml / Supertonic defect.

🧪 How was it tested?

• Root-caused from two independent device-farm crashes (same ggml-vulkan init → SIGABRT signature) + a known-good comparison (Jun 5 green run on old parakeet-cpp = CPU).
• ⚠️ I could not build the Android prebuild locally — needs the verified label to run the prebuild + Device Farm parakeet suite to confirm CPU-only loads cleanly. The readelf-style ground truth here is the Device Farm run getting past parakeet-tdt-wav.

💥 Breaking Changes

• Parakeet on Android is now CPU-only at the build level (GPU was already disabled at runtime via the engine-boundary useGPU=false, so no behavior change for callers). Re-enable once the upstream Adreno Vulkan/OpenCL ggml path is fixed.

➡️ Follow-up

• Track the upstream parakeet-cpp / ggml Adreno Vulkan/OpenCL instability (same root family as the Supertonic-Adreno abort) so GPU can be re-enabled on Android.
• A ticket should be linked (used [notask] as a placeholder).

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[Zbig9000]

#2525 can be closed because #2529 was merged and it resolved the issue completely.