M3 wiki-links: [[links]] + backlinks

- Migration 0009: note_links (source_id, target_norm). Parse [[...]] from body on
  create/update and rewrite the source's links. GET /api/notes/titles (owner
  {id,title} index for client-side resolution); GET /api/notes/<id>/backlinks.
- Frontend: titles store; LinkedText renders [[Title]] styled on cards; editor
  shows Links (outgoing, resolve/create-on-click) + Linked-from (backlinks),
  clicking navigates the editor to the target note (board + search).
- notes store: fetchOne, createTitled. DB-free link-parser tests.

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

@@ -141,6 +141,20 @@ export const useNotesStore = defineStore("notes", () => {
     reconcile(await api.del<Note>(`/api/notes/${id}/attachments/${attId}`));
   }
 
+  async function fetchOne(id: string): Promise<Note | null> {
+    try {
+      return await api.get<Note>(`/api/notes/${id}`);
+    } catch {
+      return null;
+    }
+  }
+
+  async function createTitled(title: string): Promise<Note> {
+    const created = await api.post<Note>("/api/notes", { title, body: "" });
+    reconcile(created);
+    return created;
+  }
+
   async function reorder(orderedIds: string[]): Promise<void> {
     // Optimistically assign positions matching the backend (total - index), sort,
     // then persist.
@@ -185,6 +199,8 @@ export const useNotesStore = defineStore("notes", () => {
     deleteItem,
     uploadAttachment,
     deleteAttachment,
+    fetchOne,
+    createTitled,
     reorder,
     trash,
     restore,