deferred_startup_sequence

Required order:
1. Load the smallest practical host entry.
2. Synchronously register commands and the activity-bar provider; return from `activate`.
3. Assign the activity-bar shell and wait for the post-first-frame `ready` handshake.
4. Start index discovery / sync after `ready`; if the sidebar stays closed, start after a bounded three-second fallback so startup indexing and watchers are not lost.
5. Start the language client after `ready`, with a one-second fallback so language features work when the sidebar stays closed.
6. Report incremental index progress inside the already-painted sidebar.
The ready signal and both startup paths are one-shot / idempotent.
background_startup

Status: done

Interactive page: deferred_startup_sequence