* fix(vulkan): auto-select discrete GPU and add manual device selection
On hybrid GPU systems (Intel iGPU + NVIDIA dGPU), whisper.cpp's Vulkan
backend always selected device 0 (the integrated GPU), resulting in
significantly slower performance.
Changes:
- Add detect_vulkan_devices() to enumerate all Vulkan GPUs and identify
discrete vs integrated devices
- Set GGML_VULKAN_DEVICE env var before model init to select the correct
GPU (auto-selects discrete GPU when available)
- Add whispercpp_gpu_device config option for manual device selection
- Add GPU device dropdown in Settings > Advanced for users with multiple
Vulkan GPUs
Fixes#589
* test: add coverage for Vulkan GPU device selection
- Test detect_vulkan_devices() with single/multiple GPUs
- Test _prefer_discrete_vulkan_device() preference logic
- Test GPU device selection in recognition_manager
- Verify GGML_VULKAN_DEVICE env var is set correctly
* fix(speech_recognition): pass whispercpp GPU device to pywhispercpp Model context_params
The Vulkan device-selection logic from PR #590 set the GGML_VULKAN_DEVICE
environment variable, but pywhispercpp did not pick it up. Pass the selected
GPU device through the pywhispercpp Model context_params so whisper.cpp
actually initializes the requested Vulkan device.
Fixes#589
* fix(speech_recognition): fallback when pywhispercpp lacks context_params
Older pywhispercpp releases (< ~1.4.0) reject the context_params keyword
and raise TypeError. Detect that specific failure and retry without GPU
device selection so the engine still loads on those versions.
Fixes#589
* refactor(speech_recognition): inline context_params assignment
Simplify the GPU device selection path and remove the temporary dict.
* fix(vulkan): parse real vulkaninfo GPU0: headers
detect_vulkan_devices() only recognized fictional "GPU id = N" headers,
so real vulkaninfo --summary output (GPU0:/GPU1:) returned no devices and
hybrid NVIDIA systems fell through to CUDA. Also resolve preferred device
names by GPU id instead of list position.
Fixes#589
* refactor(whispercpp): drop ineffective GGML_VULKAN_DEVICE env var
pywhispercpp ignores GGML_VULKAN_DEVICE; device selection already goes
through context_params={"gpu_device": N}. Remove the misleading env write
so maintainers do not think the env var is the selection path.
