Builds on @naqerl's arrow up/down history (previous commit), making
ArrowUp do the right thing when a queue exists.
ArrowUp/ArrowDown priority:
1. Editing a queued turn → walk older/newer through queued entries,
saving each edit; ArrowDown past the newest exits and restores the
pre-edit draft.
2. Empty composer + queued turns → ArrowUp opens the newest queued entry
for editing (the row's pencil), so Enter saves it back to the queue
instead of firing a new message — the gap the history nav had alone.
3. Otherwise → sent-message history recall (unchanged).
Also: Esc cancels an in-progress queue edit (else interrupts).
Cleanups on the integrated code: fold the browse-state reset into the
existing session-change effect (drop the duplicate ref+effect); reuse
loadIntoComposer for history recall; sort imports; add curly braces +
the runDrain sessionId dep (lint).
ce50030634