[eric] dashboard: scroll zooms the canvas over any card (Google Maps); click into a card to scroll its content

frontend/src/shared/browserRegistry.ts

@@ -25,6 +25,7 @@ export interface BrowserWebview extends HTMLElement {
   isLoading: () => boolean;
   // Optional: present on real Electron webviews; the iframe fallback lacks it, callers must ?.() it.
   isCurrentlyAudible?: () => boolean;
+  send?: (channel: string, ...args: any[]) => void;
   capturePage: (rect?: { x: number; y: number; width: number; height: number }) => Promise<ElectronNativeImage>;
   executeJavaScript: (code: string) => Promise<any>;
   sendInputEvent: (event: any) => void;

frontend/src/shared/cardScrollFocus.ts

@@ -0,0 +1,22 @@
+// The card you've clicked INTO, so plain scroll reads its content (chat transcript, web page)
+// while scroll everywhere else zooms the canvas (Google Maps model). Imperative + read on the
+// wheel handler so no re-render; cleared when you click blank canvas.
+let scrollFocusedCardId: string | null = null;
+type Listener = (id: string | null) => void;
+const listeners = new Set<Listener>();
+
+export function setScrollFocusedCard(id: string | null): void {
+  if (scrollFocusedCardId === id) return;
+  scrollFocusedCardId = id;
+  for (const l of listeners) l(id);
+}
+
+export function getScrollFocusedCard(): string | null {
+  return scrollFocusedCardId;
+}
+
+// Browser cards subscribe so they can tell their (out-of-process) guest whether plain wheel should scroll the page or zoom the canvas.
+export function onScrollFocusChange(l: Listener): () => void {
+  listeners.add(l);
+  return () => { listeners.delete(l); };
+}