fix: live audio/video format misalignment

[allen-stephen]

Live audio and video were sent and played in incorrect formats:

• Capture mic audio at 16 kHz (was 22 kHz); the Live API expects 16 kHz PCM input.
• Signal the input sample rate via mime_type 'audio/pcm;rate=16000' so the backend can interpret incoming audio correctly.
• Play back audio at 24 kHz (was 22 kHz) to match the Live API's output rate.
• Encode camera frames as JPEG to match the 'image/jpeg' mime_type
• Resample mic audio with linear interpolation instead of nearest-neighbor to reduce aliasing artifacts.