Feat v0.4.1 folders navigation tree (#23)

Add folders as a first-class concept in the Notes surface with full
CRUD, nested tree navigation, and folder-based note filtering.

Backend (script.star):
- Folder CRUD handlers: list, create, update, delete
- Move-note endpoint to reassign folder_id
- Delete cascades: orphan notes to unfiled, reparent child folders
- Stats now include unfiled and folder counts

Frontend (js/main.js):
- FolderTree component with flat-to-tree builder via useMemo
- FolderNode recursive component with expand/collapse, inline rename
- Folder state: activeFolderId, showUnfiled for sidebar filtering
- Editor folder select dropdown for moving notes between folders
- New notes inherit active folder on creation

Schema (manifest.json):
- New ext_notes_folders table (name, parent_id, creator_id, sort_order)
- 5 new API routes: GET/POST /folders, PUT/DELETE /folders/*, POST /notes/move
- Version bumped to 0.2.0

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/notes/css/main.css

@@ -39,6 +39,75 @@
   gap: 4px;
 }
 
+/* ── Folder Tree ────────────────────────── */
+.folder-tree {
+  padding: 4px 0;
+  border-bottom: 1px solid var(--border);
+  flex-shrink: 0;
+  max-height: 40%;
+  overflow-y: auto;
+}
+.folder-tree__item {
+  display: flex;
+  align-items: center;
+  gap: 4px;
+  padding: 5px 12px;
+  font-size: 13px;
+  color: var(--text-2);
+  cursor: pointer;
+  border-radius: var(--radius);
+  margin: 1px 6px;
+  transition: var(--transition);
+  user-select: none;
+}
+.folder-tree__item:hover {
+  background: var(--bg-hover);
+  color: var(--text);
+}
+.folder-tree__item--active {
+  background: var(--bg-active);
+  color: var(--text);
+  font-weight: 500;
+}
+.folder-tree__toggle {
+  width: 14px;
+  font-size: 9px;
+  text-align: center;
+  flex-shrink: 0;
+  color: var(--text-3);
+}
+.folder-tree__icon {
+  font-size: 13px;
+  flex-shrink: 0;
+}
+.folder-tree__name {
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  flex: 1;
+}
+.folder-tree__edit {
+  flex: 1;
+  font-size: 13px;
+  padding: 1px 4px;
+  border: 1px solid var(--accent);
+  border-radius: 3px;
+  background: var(--bg-surface);
+  color: var(--text);
+  font-family: var(--font);
+  outline: none;
+}
+.folder-tree__add {
+  padding: 6px 12px;
+  font-size: 12px;
+  color: var(--text-3);
+  cursor: pointer;
+  transition: var(--transition);
+}
+.folder-tree__add:hover {
+  color: var(--accent);
+}
+
 /* ── Search ──────────────────────────────── */
 .notes-search {
   padding: 8px 14px;
@@ -171,6 +240,23 @@
   align-items: center;
 }
 
+/* ── Folder select in editor ────────────── */
+.notes-editor__folder-select {
+  font-size: 12px;
+  padding: 3px 6px;
+  border: 1px solid var(--border);
+  border-radius: var(--radius);
+  background: var(--bg-raised);
+  color: var(--text-2);
+  font-family: var(--font);
+  cursor: pointer;
+  max-width: 140px;
+}
+.notes-editor__folder-select:focus {
+  outline: none;
+  border-color: var(--accent);
+}
+
 /* ── Editor Body ─────────────────────────── */
 .notes-editor__body {
   flex: 1;
@@ -291,4 +377,5 @@
 @media (max-width: 700px) {
   .notes-sidebar { width: 100%; border-right: none; border-bottom: 1px solid var(--border); max-height: 40vh; }
   .notes-app { flex-direction: column; }
+  .folder-tree { max-height: 30vh; }
 }