Make command palette defaults useful and guidance contextual

[brsbl]

Human comments

What was wrong

The blank Commands view was capped and reordered by palette usage, while blank thread search followed sidebar ordering and offered only “No recent threads” when empty. Persistent footer hints remained visible even when there was no result to act on.

What changed

• Show the full, stable command catalog before typing, with separate Threads, Actions, Settings, and Plugins groups. Exiting Threads with × and opening Commands directly produce the same view; typed queries retain relevance ranking and existing entries.
• Order existing threads and dated drafts by last updated. Distinguish loading, errors, filtered emptiness, and no matches; genuine first use offers “No threads yet” and a keyboard-accessible New thread action using the existing command runner.
• Show only the subtle Open in split hint when a desktop thread result is selected. Commands, empty/loading states, and compact layouts have no footer; existing keyboard behavior and accessible instructions remain.
• Apply the preceding approved refinements: shared responsive scope dropdown, quieter divider, and right-aligned Draft/Archived metadata. No API, SDK, CLI, or persisted-contract changes.

How you verified

• Remote CI on 75de5ebe0: all test shards, build/typecheck/lint, package smoke, and Node 24/26 compatibility smoke pass. Blocked: the raw startup bundle is 1685.3 KB against a 1685.2 KB budget (0.1 KB over). Redundant timestamp maps were removed; the budget was not raised.
• Added focused matching/order regressions, first-use Enter/pointer selection, × versus direct Commands entry, loading/error/empty states, contextual footer, shared-menu focus/keyboard behavior, and existing command/plugin coverage. All 38 CommandPalette component tests pass remotely.
• Real branch web app in Chrome for Testing 153.0.8010.36: cleared palette history, direct Commands and × exit, New thread by pointer/Enter, last-updated ordering across active/archived rows, scope selection, no matches, reload/navigation, and open/close transitions. Desktop 1440×900 and compact 390×844; compact scope selection retained the palette without hiding/inerting the app root.
• Verification gap: iOS Simulator Safari is unavailable (xcrun cannot find simctl). The compact responsive dropdown still needs that required check; this PR remains draft.

Screenshots compare the parent ab9a7f30e with the exact child head 75de5ebe0, using the same empty account fixture, no palette history, /settings/keyboard, light theme, and 1440×900 viewport. Last-updated ordering was rechecked on the final head after simplifying the comparator; no renderer errors occurred during the interaction pass.

State	Before	After
Commands before typing
No existing threads

BB-Thread-ID: thr_82jtfaq8eq

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