M1: masonry board UI — quick-add, note cards, editor, views

- notes Pinia store (load/create/pin/archive/color/trash/restore/delete) with
  view-aware reconcile; api client patch/del methods.
- colors.ts palette (10 keys → light/dark card + swatch tints).
- QuickAdd (collapsed → expand, title/body/color, click-outside/Esc to save),
  NoteCard (color tint, click-to-edit, hover action bar), NoteEditor modal,
  ColorPicker, inline Icon set (no icon dep).
- BoardView rewrite: Notes/Archive/Trash routes, CSS-columns masonry, Pinned +
  Others sections, per-view empty states, sign-out.

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

frontend/src/api/client.ts

@@ -29,4 +29,6 @@ async function request<T>(method: string, path: string, body?: unknown): Promise
 export const api = {
   get: <T>(path: string) => request<T>("GET", path),
   post: <T>(path: string, body?: unknown) => request<T>("POST", path, body),
+  patch: <T>(path: string, body?: unknown) => request<T>("PATCH", path, body),
+  del: <T>(path: string) => request<T>("DELETE", path),
 };