M6 1908b: foreground reminder delivery + recurrence/snooze UI (frontend)

Completes 1908 without Web Push. While the app is open, due reminders now
actually surface; recurring reminders + snooze/done are manageable.

- reminders store (singleton): polls /api/notes/reminders every 45s while
  the app is open; each due reminder fires ONCE as a toast (with an "Open"
  action) and, if the user opts in, a page-context OS Notification — no
  service worker, no PWA. Silently primes a stale backlog on first load;
  only announces recently-due ones. AppShell starts/stops it.
- Editor reminder section: a Repeat picker (Does not repeat / Daily /
  Weekly / Monthly / Yearly) + Done (advances a recurring reminder / clears
  a one-off) + Snooze 1h/1d, shown when a reminder is set.
- RemindersView rebuilt as a chronological list: per row a due time +
  recurrence badge + Done / 1h / 1d, click to open; plus an "Enable
  notifications" opt-in and a note that background alerts come with native.
- Note type gains `recurrence`; notes store setRecurrence /
  completeReminder / snoozeReminder.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FRgehjoz7Yv8LkUfADxACm

frontend/src/stores/notes.ts

@@ -77,6 +77,7 @@ export interface Note {
   archived: boolean;
   trashed: boolean;
   remind_at: string | null;
+  recurrence: string | null;
   labels: NoteLabel[];
   items: ChecklistItem[];
   attachments: Attachment[];
@@ -159,7 +160,9 @@ export const useNotesStore = defineStore("notes", () => {
 
   async function mutate(
     id: string,
-    changes: Partial<Pick<Note, "title" | "body" | "color" | "kind" | "pinned" | "archived" | "remind_at">>,
+    changes: Partial<
+      Pick<Note, "title" | "body" | "color" | "kind" | "pinned" | "archived" | "remind_at" | "recurrence">
+    >,
   ): Promise<void> {
     reconcile(await api.patch<Note>(`/api/notes/${id}`, changes));
   }
@@ -173,8 +176,16 @@ export const useNotesStore = defineStore("notes", () => {
   const setColor = (id: string, color: NoteColor) => mutate(id, { color });
   const setKind = (id: string, kind: NoteKind) => mutate(id, { kind });
   const setReminder = (id: string, remindAt: string | null) => mutate(id, { remind_at: remindAt });
+  const setRecurrence = (id: string, recurrence: string | null) => mutate(id, { recurrence });
   const saveEdit = (id: string, changes: { title: string; body: string; color: NoteColor }) => mutate(id, changes);
 
+  async function completeReminder(id: string): Promise<void> {
+    reconcile(await api.post<Note>(`/api/notes/${id}/reminder/complete`));
+  }
+  async function snoozeReminder(id: string, minutes: number): Promise<void> {
+    reconcile(await api.post<Note>(`/api/notes/${id}/reminder/snooze`, { minutes }));
+  }
+
   async function setLabels(id: string, labelIds: string[]): Promise<void> {
     reconcile(await api.put<Note>(`/api/notes/${id}/labels`, { label_ids: labelIds }));
   }
@@ -300,6 +311,9 @@ export const useNotesStore = defineStore("notes", () => {
     setColor,
     setKind,
     setReminder,
+    setRecurrence,
+    completeReminder,
+    snoozeReminder,
     saveEdit,
     setLabels,
     addItem,