fix:Wire resample 16khz into AudioRecorder stop recording

[Bhup-GitHUB]

Closes #3

Problem

AudioRecorder::stop_recording() claims to return "16kHz, mono, f32" audio
samples but never actually performs resampling. On Apple Silicon Macs, the
default microphone records at 48kHz. Feeding these raw samples to Whisper
(which expects exactly 16kHz) causes: incorrect transcriptions, garbled
output, or silent failures.

The resample_to_16khz() function already existed in the same file
(lines 92–114) but was never called.

Changes

File: third_party/mofa-input/src/asr/audio.rs

• Added sample_rate: u32 field to AudioRecorder struct
• Store device sample rate from cpal config in start_recording()
• Call resample_to_16khz() in stop_recording() before returning samples
• Removed empty placeholder if block and TODO comment

[Bhup-GitHUB]

@BH3GEI can you review it once?