feat: keyboard waves A/B — global shortcut registry, question row machine, Esc-cancel dictation

Wave A (owner key map): registry in src/core/keyboard.ts + KeyboardShortcuts
provider; Cmd+D dictation, Cmd+K model picker, Shift+Tab thinking cycle,
Cmd+B sidebar, Cmd+Shift+F sessions search, Alt+arrows session cycle,
Alt+Enter open, Cmd+G graph, Cmd+N new, F2 rename, ? cheat sheet. Tab
fully suppressed; Esc chain popover > dictation > abort (local stream).
Esc now CANCELS dictation (discard) — flush stays on Cmd+D/Stop. Owner
bug reports fixed: focus outline removed, Alt+Enter setState-in-render,
Cmd+F graph node search (surface-scoped lh:kbd-find).

Wave B: question dock row machine — arrows walk options + dont-know/Other
with wrap + ring highlight, Space picks (mirrors click semantics), Enter
submits when canSubmit; typing surfaces and in-dock keys keep native
behavior. aria-checked={isSel} restored on option buttons.

docs/keyboard.md records the full map.

components/new-session.tsx

@@ -116,7 +116,7 @@ export function DraftShell({
 										onStop={() => {}}
 										canSend={canSend}
 										autoFocus
-										onEscape={dictation.active ? dictation.stop : undefined}
+										onEscape={dictation.active ? dictation.cancel : undefined}
 									/>
 								</div>
 								<StatsBar