whisper : catch C++ exceptions in whisper_init_with_params_no_state (#3831)

whisper : catch C++ exceptions in whisper_init_with_params_no_state (#3831)

whisper_model_load() can throw instead of returning false: std::runtime_error
from this file (failed ggml context / no compatible buffer type), or
vk::SystemError / vk::OutOfDeviceMemoryError from the ggml-vulkan backend during
device/buffer allocation.

whisper_init_* are extern "C", so a C++ exception unwinding across that boundary
aborts non-C++ callers (Rust via whisper-rs, Go via cgo) -- on Windows
STATUS_STACK_BUFFER_OVERRUN (0xC0000409) -- even though the function already
returns NULL on failure. Wrap whisper_model_load() in try/catch and route any
throw into the existing NULL-return path.

Co-authored-by: Claude Opus 4.7 <redacted>