M2 labels frontend: sidebar shell + label filter, chips, picker, manage

- AppShell: persistent left sidebar (Notes · labels · Archive · Trash) + top bar
  (site name, admin Settings, sign out); BoardView now renders inside it.
- labels store (list/create/rename/delete); Note gains labels[]; notes store
  gains setLabels + label-aware reconcile + /api/notes?label= loading.
- /label/:id route → label-filtered board.
- LabelPicker (tag a note, create-on-the-fly) in the editor; label chips shown
  on cards and in the editor; LabelsModal to create/rename/delete labels.
- api client PUT; new icons (note/tag/pencil/plus/check); nav-link styles.

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

frontend/src/stores/labels.ts

@@ -0,0 +1,46 @@
+import { defineStore } from "pinia";
+import { ref } from "vue";
+import { api } from "../api/client";
+
+export interface Label {
+  id: string;
+  name: string;
+}
+
+export const useLabelsStore = defineStore("labels", () => {
+  const items = ref<Label[]>([]);
+  const loaded = ref(false);
+
+  function sort() {
+    items.value.sort((a, b) => a.name.localeCompare(b.name));
+  }
+
+  async function load(): Promise<void> {
+    const res = await api.get<{ labels: Label[] }>("/api/labels");
+    items.value = res.labels;
+    loaded.value = true;
+  }
+
+  async function create(name: string): Promise<Label> {
+    const label = await api.post<Label>("/api/labels", { name });
+    if (!items.value.some((lb) => lb.id === label.id)) {
+      items.value.push(label);
+      sort();
+    }
+    return label;
+  }
+
+  async function rename(id: string, name: string): Promise<void> {
+    const updated = await api.patch<Label>(`/api/labels/${id}`, { name });
+    const idx = items.value.findIndex((lb) => lb.id === id);
+    if (idx >= 0) items.value[idx] = updated;
+    sort();
+  }
+
+  async function remove(id: string): Promise<void> {
+    await api.del(`/api/labels/${id}`);
+    items.value = items.value.filter((lb) => lb.id !== id);
+  }
+
+  return { items, loaded, load, create, rename, remove };
+});