fan-control: Override slider now tracks live fan speed while unlocked [ci skip]

The dashboard Override slider used to show a stale stored % (e.g. 5%) while the
fans were actually at ~53%, which was confusing. Add
automation.r730_fan_override_track_live_speed_while_unlocked: while unlocked it
mirrors the live commanded % (sensor.r730_fan_control_target) into the Override,
so it always shows the actual absolute fan speed and updates as the fan moves.
While locked it stops tracking and is the user's editable setpoint. The readout
under the slider now shows the live "% · rpm" (actual, not an estimate). HA-side
only; daemon unchanged. Verified live: slider forced to 10 → synced to 58 target.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/runbooks/fan-control.md

@@ -16,7 +16,13 @@ Drive the fans from **dashboard-it → "Server" view → Fans**. The view is
 deliberately minimal — it shows the current **fan speed** (% of capacity +
 absolute RPM) and two controls:
 
-- **Override %** (`input_number.r730_fan_manual_pct`) — the fixed fan % to hold.
+- **Override %** (`input_number.r730_fan_manual_pct`) — the fan % to hold. While
+  **unlocked** it continuously mirrors the live commanded fan %, so it always
+  shows the actual *absolute* speed and updates as the fan moves (NOT a stale
+  value or a delta) — `automation.r730_fan_override_track_live_speed_while_unlocked`
+  syncs it to `sensor.r730_fan_control_target` (guarded to ignore
+  unavailable/unknown). While **locked** it stops tracking and becomes your
+  editable setpoint. A readout under the slider shows the live `% · rpm`.
 - **Lock — freeze speed** (`input_boolean.r730_fan_lock`) — turn the algorithm
   off and hold a fixed speed. Toggling it **ON** snapshots the *current*
   commanded % into Override and switches the daemon to `manual`