Harden codebase: fix security, quality, and maintainability issues
- Replace dangerous unwrap() with proper error handling (storage.rs, webdav.rs)
- Add atomic writes (temp + rename) for config, sync state, and metadata files
- Add path traversal validation in sync executor
- Add workspace path validation in Tauri commands
- Add input size limits for task titles, descriptions, and list names
- Add file download size limit (10MB) to WebDAV get_file
- Fix move_task rollback to log failures instead of silently ignoring
- Fix JSON serialization unwrap in Tauri create_remote_workspace
- Fix swallowed errors in sync queue backup, metadata writes, sync state load
- Extract hardcoded strings into named constants (filenames, extensions, limits)
- Use REQUEST_TIMEOUT/CONNECT_TIMEOUT constants in WebDAV client builder
- Fix frontend: clear taskStack when viewed task is deleted or list is switched
- Fix frontend: surface credential loading and focus listener errors
https://claude.ai/code/session_01F67yfLLmSaBtT7aKKNus1M
a12deb5182