Audio Recording Stops After 5 Seconds

## Description
Audio recording stops after ~5 seconds when holding the trigger key, making it impossible to record longer content.

## Environment
- macOS 15.6 (Apple Silicon)
- Hex version 0.2.5
- Built-in microphone

## Steps to Reproduce
1. Hold trigger key to record
2. Keep holding and speaking
3. Recording stops at ~5 seconds despite holding key

## Expected vs Actual
- **Expected**: Recording continues while key is held
- **Actual**: Recording stops after 5 seconds

## Root Cause
Console shows audio session switching categories during recording, causing this error:
`error 10:15:15.305568-0700 Hex BuiltInMicrophoneDevice: Abandoning I/O cycle because reconfig pending`

The app switches from `Record_WithBluetooth` → `PlayAndRecord_WithBluetooth` → `MediaPlayback`, which kills the recording.

## Logs
Recording timeline from console:
`10:15:09.208 - Recording starts
10:15:09.373 - Category: Record_WithBluetooth
10:15:09.422 - Category: PlayAndRecord_WithBluetooth
10:15:15.305 - ERROR: "Abandoning I/O cycle because reconfig pending"
10:15:15.306 - Category: MediaPlayback (recording stops)`

## Impact
App is unusable for recordings longer than 5 seconds. Both press-and-hold and double-tap modes are affected.

The issue provides no source file or test location. Start by reproducing the five-second stop on macOS and tracing the audio-session category transitions shown in the console log; then locate the recording lifecycle that triggers them. Done means both press-and-hold and double-tap recordings continue while recording is active, without the reported I/O reconfiguration failure.

Written by the indexing model from the issue text.