chore: remove unnecessary optimization (#20)

Reviewed-on: #20

docs/TODO.md

@@ -0,0 +1,18 @@
+# TODO
+
+## `BackendEvent::SyncProgress`
+
+File: `crates/signed_state/src/backend.rs`
+
+Kept intentionally. The progress pipeline (the `SyncProgress` variant, the `sync_progress`
+field and its accessor, and the progress task in `sync_bootstrap`) is retained for a planned
+sync progress indicator. No subscriber exists yet. Do not remove it without revisiting that
+plan.
+
+## `login` / `logout` family
+
+File: `crates/signed_state/src/backend.rs`
+
+No UI path calls these. `import_dialog::open` is an empty stub. Decide whether to
+delete the family (`login`, `login_with_new_identity`, `login_with_nsec`,
+`login_with_bunker`, `logout`) or wire the stub to `Backend::login`.