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/views/BoardView.vue

@@ -47,6 +47,16 @@ function closeEditor() {
   editing.value = null;
 }
 
+async function onNavigate(id: string) {
+  const found = notes.items.find((n) => n.id === id);
+  if (found) {
+    editing.value = found;
+    return;
+  }
+  const fetched = await notes.fetchOne(id);
+  if (fetched) editing.value = fetched;
+}
+
 const draggingId = ref<string | null>(null);
 function onDragStart(note: Note) {
   draggingId.value = note.id;
@@ -125,6 +135,6 @@ async function onDrop(target: Note) {
   </div>
 
   <template v-if="editing">
-    <NoteEditor :note="editing" @close="closeEditor" />
+    <NoteEditor :note="editing" @close="closeEditor" @navigate="onNavigate" />
   </template>
 </template>