feat: notifications inbox page

The bell only ever showed the last 30; add a full paginated /notifications
page, per-notification mark-read, and a shared notificationHref helper so
the bell and the page route identically instead of duplicating the logic.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/lib/notification-links.ts

@@ -0,0 +1,15 @@
+export type NotificationType = "follow" | "comment" | "reply" | "reaction" | "rating" | "mention";
+
+export type NotificationLinkable = {
+  type: NotificationType;
+  recipeId: string | null;
+  actorUsername: string | null;
+};
+
+/** Where clicking a notification should navigate to. Shared by the bell dropdown
+ * and the full notifications page so the two never drift apart. */
+export function notificationHref(n: NotificationLinkable): string {
+  if (n.type === "follow") return n.actorUsername ? `/u/${n.actorUsername}` : "#";
+  if (n.recipeId) return `/recipes/${n.recipeId}`;
+  return "#";
+}