feat: native desktop notifications + rowboat:// deep links

Adds INotificationService with an Electron implementation, plus a deep-link
dispatcher (rowboat://) for routing notification clicks back into the app.

Notifications:
- New `notify-user` skill + builtin tool. Title, message, optional primary
    link, optional secondary actions. Supports https:// (opens in browser) and
    rowboat:// (opens in app) targets.
- ElectronNotificationService holds strong refs to active Notification
    instances so click handlers survive GC (otherwise macOS click silently
    no-ops).
- Calendar meeting notifier fires 1-min warnings with "take notes" /
    "join + take notes" actions backed by deep links.

Deep links (rowboat://):
- forge.config.cjs declares the protocol; main.ts wires single-instance
    lock, setAsDefaultProtocolClient, open-url (mac), second-instance (win/
    linux), and first-launch argv extraction.
- New deeplink.ts dispatcher with dispatchUrl(url): main-handled actions
    (rowboat://action?type=...) vs renderer navigation (rowboat://open?...)
    via app:openUrl IPC. Includes pending-URL buffering for first-launch
    delivery before the renderer is ready.
- Renderer parseDeepLink supports file / chat / graph / task /
    suggested-topics targets.
- New app:consumePendingDeepLink IPC for renderer one-time drain on mount.

Refactor: extractConferenceLink moved out of calendar-block.tsx into
shared lib/calendar-event.ts (used by both the block and the take-notes
deep-link handler)

apps/x/packages/shared/src/ipc.ts

@@ -299,6 +299,28 @@ const ipcSchemas = {
     }),
     res: z.null(),
   },
+  'app:openUrl': {
+    req: z.object({
+      url: z.string(),
+    }),
+    res: z.null(),
+  },
+  'app:takeMeetingNotes': {
+    req: z.object({
+      // Pass the raw calendar event JSON through; renderer adapts to its existing flow.
+      event: z.unknown(),
+      // When true, the renderer should also open the meeting URL (Zoom/Meet/etc.)
+      // in addition to triggering the take-notes flow.
+      openMeeting: z.boolean().optional(),
+    }),
+    res: z.null(),
+  },
+  'app:consumePendingDeepLink': {
+    req: z.null(),
+    res: z.object({
+      url: z.string().nullable(),
+    }),
+  },
   'granola:getConfig': {
     req: z.null(),
     res: z.object({