v0.5.1

Fix: BLE reconnect reliability

Fixes an issue where the integration would fail to reconnect after a BLE disconnect and never recover — hammering the adapter with rapid connect attempts until BlueZ crashed.

Changes

• Exponential backoff now works: previously the backoff timer reset before every connect attempt (as long as the device was advertising), so it never actually grew. Now it only resets after a successful connect. Backoff: 5s → 10s → 20s → 40s → 80s → 160s → 300s max.
• Connection slot leak fixed: if establish_connection succeeded but a later step (MTU negotiation, notifications, bind) failed, the BLE connection was dropped without calling disconnect() — leaking a BlueZ connection slot. Now properly cleaned up.
• Robust disconnect: always attempts disconnect() even when is_connected reports False, since BlueZ may still hold the connection slot.
• Disconnect timeout: added 5s timeout to disconnect in the connect error handler (was hanging up to 10s on unreachable devices).
• Backoff visibility: reconnect warnings now log the wait duration (waiting 20s before reconnect) for easier debugging.