Fix native VehicleDecoder leak in DashKitDataSource

[ehoeve786]

Problem

DashKitDataSource creates a native VehicleDecoder (via CanFrameDecoder) per connection but never frees it — CanFrameDecoder.destroy() has no callers. Every DashKit connect/reconnect from ConnectionViewModel (manual connect, foreground restore after a dead link) leaks a full decoder with its parsed DBC tables. CommaDataSource already frees its decoder in disconnect(); the DashKit path was missing it.

Fix

• DashKitDataSource.disconnect() calls decoder.destroy() after removing the GATT listener.
• CanFrameDecoder.destroy() zeroes the handle; decodeFrame() returns null once destroyed and the caller drops the packet. Both are @Synchronized, so a notification already in flight on the binder thread during teardown can't decode with a freed pointer.

BLE-level auto-reconnects (e.g. DashKit reboot) are unaffected — the data source and decoder persist across those as before.

Testing

Samsung Galaxy S23 Ultra, Android 16. dumpsys meminfo taken ~1 min apart across repeated DashKit connect/disconnect cycles:

• Stock v0.9.2: native heap 17.0 → 78.6 MB (+61.6 MB, ≈8–9 leaked decoders)
• v0.9.1 + this fix: native heap 21.0 → 22.3 MB (+1.2 MB, flat)

Host build of VehicleDecoder with config_dashkit.json: one decoder ≈ 7.2 MB native; 10 cycles leak 71.6 MB without destroy(), 0.05 MB with it.

🤖 Generated with Claude Code

meminfo-fixed-v0.9.1-after.txt
meminfo-fixed-v0.9.1-before.txt
meminfo-stock-v0.9.2-after.txt
meminfo-stock-v0.9.2-before.txt