Add KDoc to the single-interface feature API modules

Cover the last remaining interfaces across features/announcement, cachecleaner,
call, contentscanner, createroom, knockrequests, lockscreen, rolesandpermissions,
startchat, userprofile and viewfolder, with their members and parameters.

Grouped into one commit rather than eleven near-empty ones, per the AGENTS.md rule
about tiny commits.

This completes every features/* api module.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

features/lockscreen/api/src/main/kotlin/io/element/android/features/lockscreen/api/LockScreenService.kt

@@ -17,6 +17,9 @@ import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.onEach
 
+/**
+ * Exposes the app lock state: whether a PIN or biometric lock is set up, whether it is mandatory, and whether the app is locked right now.
+ */
 interface LockScreenService {
     /**
      * The current lock state of the app.