App 2.34.0: set the chosen drive mode again when the car starts

The car falls back to its own default mode at every start. With "Set at
start" (on by default), the service sets the mode last chosen on
Settings and confirmed by the car again, once, while the car is in P at
0 km/h, and gives up as soon as the car leaves P or after two minutes
(DriveModeWrite.atStart, unit-tested). The buttons and the start share
the write and read-back (DriveModeSetter). Not tried on the car.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LhzAVaUyqcw5PkGjz4mWW6

README.md

@@ -84,7 +84,7 @@ with the server using a token of its own, obtained by pairing with a phone (belo
 | **Charging** | The current session (SOC, voltage, current, power, energy into the battery and from the grid, time, cost) and its SOC/power curve |
 | **Live data** | Live data on/off, ABRP credentials for sending directly from the car, upload frequency |
 | **Server** | Server URL, pairing by QR code, ingest token, installation ID, config import |
-| **Settings** | Drive mode (Eco, Normal, Sport, Snow, Custom: changes only in P at a standstill; the highlighted one is what the car reports), full screen, voice key, tyre pressure unit, accent colour, battery (manual SoH, usable capacity), charging price, entry on the phone, version, update check, install from USB stick, About |
+| **Settings** | Drive mode (Eco, Normal, Sport, Snow, Custom: changes only in P at a standstill; the highlighted one is what the car reports; with "Set at start" the last confirmed choice is set again when the car starts, while it is still in P), full screen, voice key, tyre pressure unit, accent colour, battery (manual SoH, usable capacity), charging price, entry on the phone, version, update check, install from USB stick, About |
 | **Logs** | Update log (every install step), upload log |
 
 - **Opening the app:** the MG4 launcher does not list third-party apps. **Double-press the