keyboard: the one-Esc law — a surfaced layer claims at the document level (keyboard 4 of 4)

Owner ruling (keyboard round 2026-10-06): Esc (or any key) does ONE
action, on the topmost active layer. The plan-open-while-dictating
double-act was the symptom: the plan popup listened at WINDOW level
with no claim, and same-node window listeners all fire — the global
chain (registered first) cancelled the dictation while the plan's own
listener closed the plan. One Esc, two actions.

The law (now the house pattern, documented at the chain):
- field-level handlers claim at their element (focus in a field: the
  field's action) — unchanged, already correct
- every SURFACED layer claims at the DOCUMENT level with preventDefault
  + stopPropagation — document fires before the window chain, so the
  chain stays silent under any surface
- the window chain is the bottom-up fallback: dictation (a live capture,
  NOT a surface — it survives the Esc that closes a plan or overlay),
  then abort (escAbortTarget layers its own targets)

Converted to the claim: plan popup, session overlay, chain table,
settings dialog, setup dialog, the delete/abort dialogs (window-level
stopPropagation was never enough — same-node listeners all fire), and
the stats popover. Popovers (popover-dismiss), menus, model picker, and
the sidebar context menu already claimed correctly.

1427 tests, tsc, lint, build green.

components/setup-dialog.tsx

@@ -304,6 +304,12 @@ export function SetupDialog({
 		if (!open) return;
 		const onKey = (e: KeyboardEvent) => {
 			if (e.key !== "Escape") return;
+			// THE ONE-ESC LAW (owner, keyboard round 2026-10-06): claim at
+			// the document level before the layered dismissal — every branch
+			// below acts, so the window chain (dictation → abort) must
+			// never also fire. One Esc, one action.
+			e.preventDefault();
+			e.stopPropagation();
 			if (keyMenuOpen) {
 				setKeyMenuOpen(false);
 				return;
@@ -319,10 +325,10 @@ export function SetupDialog({
 			if (t.closest("[data-lh-menu]") || t.closest(`[data-testid="${triggerTestid}"]`)) return;
 			setOpenMenu(null);
 		};
-		window.addEventListener("keydown", onKey);
+		document.addEventListener("keydown", onKey);
 		document.addEventListener("pointerdown", onPointerDown);
 		return () => {
-			window.removeEventListener("keydown", onKey);
+			document.removeEventListener("keydown", onKey);
 			document.removeEventListener("pointerdown", onPointerDown);
 		};
 	}, [open, onClose, openMenu, keyMenuOpen]);