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/keyboard-shortcuts.tsx

@@ -9,7 +9,8 @@
  *   Shift+Tab cycles the thinking level instead.
  * - Esc is a layered dismiss: topmost popover first (popovers stopPropagation
  *   on their own Esc — usePopoverDismiss + ModelControl), then dictation
- *   stop, then abort of an in-flight turn.
+ *   CANCEL (discard the transcript, owner 2026-09-17 round 3), then abort of
+ *   an in-flight turn.
  * - Global actions dispatch lh:kbd-<action> window events; surfaces that are
  *   mounted listen (the lh:chat-renamed pattern). A surface that isn't
  *   mounted simply doesn't listen — an F2 on the graph view is a no-op, not
@@ -71,7 +72,7 @@ export function KeyboardShortcuts() {
 				// abort seam in Chat decides what's honestly stoppable).
 				if (isDictationActive()) {
 					e.preventDefault();
-					window.dispatchEvent(new CustomEvent("lh:kbd-stop-dictation"));
+					window.dispatchEvent(new CustomEvent("lh:kbd-cancel-dictation"));
 					return;
 				}
 				window.dispatchEvent(new CustomEvent("lh:kbd-abort-turn"));