feat: add dedicated notifications page

Replace the bell popover with an RTL notification inbox, inline Markdown details, read filters, and explicit destination and delete actions. Remove retired email-link screens and client calls.

src/lib/types.ts

@@ -240,16 +240,20 @@ export interface NotificationSchema {
   type: string;
   title: string;
   message: string;
+  has_body: boolean;
   level: "info" | "success" | "warning" | "error";
   created_at: string;
   is_seen: boolean;
-  delete_on_seen: boolean;
   action_url?: string | null;
   entity_type?: string | null;
   entity_id?: string | number | null;
   meta?: Record<string, unknown>;
 }
 
+export interface NotificationDetailSchema extends NotificationSchema {
+  body_markdown?: string | null;
+}
+
 export interface NotificationListSchema {
   count: number;
   unread_count: number;