Unit 5. The dock's first working bay:
- 24-segment ladder fed by `MicMeterFraction` — the MEASURED display level (already scaled by the
volume and zeroed when muted), never the gain setting.
- Fader in dB via `MicVolumeDb` (−60 … +6, 0 = unity) with a mono-weight readout
(`MicVolumeDbLabel`), so "−6.0 dB" is what the creator reads instead of "0.50".
- Mute button whose dot uses the existing MicStatusBrush; clicking the device name opens the mic
picker, so the label stays the control (the KISS rule: one place to change the mic).
The preview's own mic row stays for now — it is removed in the final unit, after the dock bays are
complete, so nothing is lost if a bay misbehaves.
Guard: MicBayTests — the bay binds the dB face and the measured level (not the gain), the fader
range IS the scale's range, the VM surface exists, and mute still zeroes the ladder.