Fix wave chunk 1: cross-surface settings signal, dialog scroll-lock, noneRow retired

- lh:settings-saved CustomEvent (the lh:chat-renamed pattern, owner
  ruling): every writer (composer save, SetupDialog save, the settings
  write seam — one dispatch point carrying the section) notifies after a
  successful PUT; every reader re-reads its own seam: ModelControl's
  record read, the Agent section's slots/catalog, and chat.tsx's
  configured state (clearing slots mid-session now surfaces the setup
  CTA without a reload). Self-notifications re-read idempotently.
- MenuShell now announces lh:menu-open/lh:menu-close (still placement-
  only); the settings dialog's content column locks (overflow-hidden,
  count-based) while any menu is open — wheel-scrolling with a dropdown
  down is dead; the re-place-on-scroll fallback stays for un-lockable
  surfaces.
- The settings thinking menus' 'Default' noneRow is retired (owner:
  the unset state can't re-enter once chunk 2's auto-populate lands; no
  unpin is needed).
- Live-caught regression from the MenuShell migration fixed: the
  composer's outside-click handler never learned the portaled menu body
  isn't a container descendant — menu-row pointerdowns counted as
  outside and ATE THE PICK (composer picks have been dead for pointer
  users since 221c99d); rows now carve out via [data-lh-menu], the
  settings sections' discipline.
- Item 4 (resolved-level display for legacy records) deferred to chunk 2
  per owner ruling — the payload omits the level for legacy no-level
  records and DEFAULT_THINKING_ORDER was server-only (now in the core
  barrel via bd68486, exactly the seam chunk 2 needs).

components/menu-shell.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import { useLayoutEffect, useRef, useState, type ReactNode, type RefObject } from "react";
+import { useEffect, useLayoutEffect, useRef, useState, type ReactNode, type RefObject } from "react";
 import { createPortal } from "react-dom";
 
 /**
@@ -43,6 +43,16 @@ const CAP_VH = 0.6; // 60vh — the graph pattern's cap
 const MIN_USABLE = 96; // floor: a shorter cap is an unusable sliver; the
 // cap then overflows the edge instead of crushing the menu
 
+/** A MenuShell mounted = a dropdown open (fix wave, owner ruling:
+ *  the settings dialog's content column locks while any menu is down —
+ *  no scrolling under a dropdown). The shell stays placement-only: it
+ *  just ANNOUNCES, surfaces decide what to do with the fact (the
+ *  settings dialog locks; anything un-lockable keeps the re-place-on-
+ *  scroll fallback below). Count-based: overlapping menus open/close in
+ *  any order and the accounting stays balanced. */
+export const MENU_OPEN_EVENT = "lh:menu-open";
+export const MENU_CLOSE_EVENT = "lh:menu-close";
+
 export type MenuSide = "up" | "down";
 export type MenuAlign = "left" | "right";
 
@@ -116,6 +126,14 @@ export function MenuShell({
 	const menuRef = useRef<HTMLDivElement>(null);
 	const [placed, setPlaced] = useState<MenuPlacement | null>(null);
 
+	// Announce open↔close for lockable surfaces (see MENU_OPEN_EVENT).
+	useEffect(() => {
+		window.dispatchEvent(new CustomEvent(MENU_OPEN_EVENT));
+		return () => {
+			window.dispatchEvent(new CustomEvent(MENU_CLOSE_EVENT));
+		};
+	}, []);
+
 	const anchor = () => {
 		if (anchorRef) return anchorRef.current;
 		if (anchorTestid !== undefined) return document.querySelector(`[data-testid="${anchorTestid}"]`);