#22238: Android: security hardening to prevent screenshots of manual gateway settings

## Summary - Set `FLAG_SECURE` on the bottom sheet window while the Advanced manual gateway section is expanded - Prevents screenshots and screen recording of sensitive connection credentials (host, port, gateway token, TLS config) - Flag is scoped to the `AnimatedVisibility` composable — automatically clears when the section collapses or the sheet is dismissed ## Test plan - [x] Open Settings → expand Advanced manual gateway section → verify screenshots are blocked - [x] Collapse the section or dismiss the sheet → verify screenshots work again - [x] Verify no regressions in other settings sections 🤖 Generated with [Claude Code](https://claude.com/claude-code) <!-- greptile_comment --> <h3>Greptile Summary</h3> This PR adds screenshot prevention to the Advanced manual gateway settings section by setting `FLAG_SECURE` on the bottom sheet window. The flag is scoped to the `AnimatedVisibility` block containing sensitive connection details (host, port, gateway token, TLS config) and automatically clears when the section collapses. **Key changes:** - Adds `DisposableEffect` inside `AnimatedVisibility` to manage `FLAG_SECURE` lifecycle - Uses `LocalView.current.parent as? DialogWindowProvider` to access the `ModalBottomSheet` window - Safe null handling ensures graceful fallback if window reference is unavailable **Implementation notes:** - The window reference retrieval uses safe casting and null-safe calls, so if the `DialogWindowProvider` cast fails, the feature silently degrades without crashes - `DisposableEffect(Unit)` correctly triggers when content enters/exits composition as `AnimatedVisibility` adds/removes content based on visibility state <h3>Confidence Score: 4/5</h3> - This PR is safe to merge with low risk - it adds a security hardening feature with proper error handling - The implementation follows Android best practices for screenshot prevention using `FLAG_SECURE`, includes proper lifecycle management via `DisposableEffect`, and uses defensive null-safe programming. The approach gracefully degrades if the window reference is unavailable. The only minor concern is that the window reference retrieval pattern (`LocalView.current.parent as? DialogWindowProvider`) may not work in all Compose contexts, but the safe casting ensures this won't cause crashes - it will simply fail silently without blocking screenshots - No files require special attention _{Last reviewed commit: 1b72ff0} <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} <!-- /greptile_comment -->