Replace all JSON file storage (connections, secrets, history, AI config,
conversations, sidebar layout) with a single SQLite database (dbx.db).
Auto-migrates existing JSON data on first launch, renaming old files to
.bak. Remove keyring dependency — passwords now stored in SQLite.
Introduce src-web (axum HTTP server) exposing all 43 database operations
as REST APIs with SSE streaming for AI, transfers, and SQL file execution.
Frontend adapts automatically between Tauri and HTTP backends via api.ts.
Includes password authentication, Docker packaging, and login page.
t8y2