## Why

The recorder generates many short false-positive recordings (360 bytes to ~4KB) triggered by noise, static, or weak signals. Multiple channels often fire simultaneously, suggesting wideband interference or poor channel isolation. The current config uses the default FFT size (512) and default squelch SNR threshold (9.54 dB), both of which are too permissive for noisy CB monitoring at 27 MHz.

## What Changes

- Increase `fft_size` to improve channel selectivity and reduce adjacent-channel false triggers
- Add `squelch_snr_threshold` per channel to raise the signal-to-noise requirement for squelch opening
- Uncomment and update the `fft_size` setting (currently commented out at 1024, defaulting to 512)

## Capabilities

### New Capabilities
- `false-positive-reduction`: RTLSDR-Airband configuration tuning to minimize noise-triggered recordings via FFT size and squelch SNR threshold adjustments

### Modified Capabilities

_(none)_

## Impact

- **Configuration**: Changes to `rtl_airband.conf` only — no new services or code
- **Pi resources**: Higher `fft_size` increases CPU usage slightly; monitor after deployment
- **Recording behavior**: Fewer but higher-confidence recordings; very weak legitimate signals may be missed