[matheuscardosoj]

Scope

Addresses the maintainer feedback that is not already present in master:

• Persist and restore the preferred startup account, with a minimal settings selector and compatibility for existing account files.
• Create the settings and lock windows outside synchronous callbacks, serialized to avoid concurrent WebView2 construction.
• Destroy a lock screen whose creation races a successful unlock.

The current master already includes the asynchronous account-management commands and idempotent autostart disablement, so they are intentionally absent from this focused diff.

Closes and replaces #26 after its head branch was renamed in the fork.

Validation

• cargo test --manifest-path src-tauri/Cargo.toml --locked — 102 passed.
• cargo clippy --manifest-path src-tauri/Cargo.toml --all-targets -- -D warnings -A unused_mut passed. unused_mut is a pre-existing Windows-only warning in master.
• git diff --check passed.