Architecture: split the 1,500-line TeslaBleController and move the per-vehicle protocol state machine into core #118

Problem

TeslaBleController.kt is 1,483 lines. Its inner class VehicleLink (L608-L1442,`` about 840 lines) covers all of these, driven by android.os.Handler runnables:

• transport lifecycle, reconnection and backoff;
• session handshakes, the pending-request table and encrypted command I/O;
• the pairing state machine and whitelist slot resolution;
• polling cadence, history recording and logging.

The outer class adds scanning and discovery, vehicle persistence, selection and the UI state.

• It is the most-changed file in the repo (touched by 50 of 250 non-merge commits) and has no tests. "Controller state-machine tests" is still open in the master plan.
• detekt was fitted to the class instead of the other way round. LargeClass: 700 carries the comment "VehicleLink is one cohesive per-car state machine… splitting it would scatter that state", and TooManyFunctions.thresholdInClasses is set to 45 (config/detekt/detekt.yml).
• It undercuts the library goal. The master plan says core becomes a reusable Tesla BLE library after v1. But what a library user needs lives in the Android app: per-domain handshakes, request/response correlation, anti-replay windows, re-handshake and resync, add-key with whitelist confirmation, and polling cadence. A published core would offer only primitives.
• Several current bugs come from this shape: BLE: GATT callbacks mutate shared state from Binder threads, and GATT operations aren't serialized #110, Protocol: replies are routed by trial-decoding; car faults and session resyncs are silently dropped #111, Polling: Infotainment is polled every 10 s whenever the car is awake, which may keep it from sleeping #112.

Proposal

• Add a platform-agnostic VehicleClient to core, one instance per car:
  • input: a transport interface (incoming: Flow<ByteArray>, send(ByteArray)), an injectable clock and an injectable CoroutineScope/dispatcher;
  • output: state: StateFlow<VehicleState> and suspend functions (handshake(domain), wake(), readCharge(), pair(key));
  • session and pairing logic written as explicit state machines.
• Keep Android-specific parts in app: TeslaGattClient (the Android transport), scanning, the foreground service, persistence and UI mapping.
• Unit-test the client against FakeCarProtocol, moved into a core test fixture, using kotlinx-coroutines-test virtual time. That covers retries, timeouts, faults and pairing without an emulator.
• Once the class is split, restore detekt's default LargeClass and TooManyFunctions thresholds.

Related: #108 (the KMP path).