Fix: Add null safety for doorState property to prevent crash with Yale Assure Lock 2 (#165)

The plugin was crashing with `Cannot read properties of undefined
(reading 'includes')` when used with Yale Assure Lock 2 devices. The
issue occurred because the lock's API response contains a lockStatus
object like `{"status":"unknown"}` without a `doorState` property, but
the code assumed this property would always exist.

The crash happened in the `parseStatus` method when trying to call
`.includes()` on the undefined `doorState`:

```typescript
// This would crash when doorState is undefined
this.lockStatus.doorState.includes('open')
this.lockStatus.doorState.includes('closed')
```

The fix adds optional chaining to safely handle cases where `doorState`
is undefined:

```typescript
// Safe version that returns undefined instead of crashing
this.lockStatus.doorState?.includes('open')
this.lockStatus.doorState?.includes('closed')
```

This minimal change:
- Prevents the crash by gracefully handling undefined `doorState`
- Maintains backward compatibility for locks that do provide `doorState`
- Preserves all existing functionality and logic flow
- Allows the plugin to continue reading battery status and other lock
information

The contact sensor functionality will fall back to the existing
`ContactSensorState` when `doorState` is unavailable, ensuring the
plugin remains functional even without door state information.

Fixes #127.

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Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: donavanbecker <[email protected]>
Co-authored-by: Donavan Becker <[email protected]>

Author: Copilot

src/devices/lock.ts

@@ -208,9 +208,9 @@ export class LockMechanism extends deviceBase {
             ? this.hap.Characteristic.ContactSensorState.CONTACT_NOT_DETECTED
             : this.lockStatus.state.closed
               ? this.hap.Characteristic.ContactSensorState.CONTACT_DETECTED
-              : this.lockStatus.doorState.includes('open')
+              : this.lockStatus.doorState?.includes('open')
                 ? this.hap.Characteristic.ContactSensorState.CONTACT_NOT_DETECTED
-                : this.lockStatus.doorState.includes('closed')
+                : this.lockStatus.doorState?.includes('closed')
                   ? this.hap.Characteristic.ContactSensorState.CONTACT_DETECTED
                   : this.ContactSensor.ContactSensorState
           await this.debugLog(`ContactSensorState: ${this.ContactSensor.ContactSensorState}`)