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/script.star

@@ -1,4 +1,4 @@
-# Notes — Starlark Backend (v0.1.0)
+# Notes — Starlark Backend (v0.2.0)
 #
 # Markdown notes surface using ext_data.
 #
@@ -76,6 +76,27 @@ def on_request(req):
     if method == "DELETE" and path.startswith("/notes/"):
         return _delete_note(path[len("/notes/"):], req)
 
+    # POST /notes/move
+    if method == "POST" and path == "/notes/move":
+        return _move_note(req)
+
+    # ── Folder routes ──────────────────────────
+    # GET /folders
+    if method == "GET" and path == "/folders":
+        return _list_folders()
+
+    # POST /folders
+    if method == "POST" and path == "/folders":
+        return _create_folder(req)
+
+    # PUT /folders/:id
+    if method == "PUT" and path.startswith("/folders/"):
+        return _update_folder(path[len("/folders/"):], req)
+
+    # DELETE /folders/:id
+    if method == "DELETE" and path.startswith("/folders/"):
+        return _delete_folder(path[len("/folders/"):])
+
     return _resp(404, {"error": "not found"})
 
 
@@ -200,6 +221,102 @@ def _delete_note(note_id, req):
     return _resp(200, {"archived": True})
 
 
+# ═══════════════════════════════════════════════
+#  Move note between folders
+# ═══════════════════════════════════════════════
+
+def _move_note(req):
+    body = json.decode(req.get("body", "{}"))
+    note_id = _str(body.get("note_id", ""))
+    folder_id = _str(body.get("folder_id", ""))
+    if not note_id:
+        return _resp(400, {"error": "note_id required"})
+    existing = db.query("notes", filters={"id": note_id}, limit=1)
+    if not existing:
+        return _resp(404, {"error": "note not found"})
+    ok = db.update("notes", note_id, {"folder_id": folder_id, "updated_at": "now"})
+    if not ok:
+        return _resp(500, {"error": "move failed"})
+    rows = db.query("notes", filters={"id": note_id}, limit=1)
+    return _resp(200, rows[0] if rows else {})
+
+
+# ═══════════════════════════════════════════════
+#  Folder CRUD
+# ═══════════════════════════════════════════════
+
+def _list_folders():
+    rows = db.query("folders", order="sort_order", limit=500)
+    items = []
+    for r in (rows or []):
+        items.append({
+            "id":         r.get("id", ""),
+            "name":       r.get("name", ""),
+            "parent_id":  r.get("parent_id", ""),
+            "sort_order": _int(r.get("sort_order", 0)),
+            "creator_id": r.get("creator_id", ""),
+            "created_at": r.get("created_at", ""),
+        })
+    return _resp(200, {"data": items})
+
+
+def _create_folder(req):
+    body = json.decode(req.get("body", "{}"))
+    user_id = req.get("user_id", "")
+    name = _str(body.get("name", ""))
+    if not name:
+        return _resp(400, {"error": "name required"})
+    row = db.insert("folders", {
+        "name":       name,
+        "parent_id":  _str(body.get("parent_id", "")),
+        "creator_id": user_id,
+        "sort_order": _int(body.get("sort_order", 0)),
+    })
+    return _resp(201, row)
+
+
+def _update_folder(folder_id, req):
+    body = json.decode(req.get("body", "{}"))
+    existing = db.query("folders", filters={"id": folder_id}, limit=1)
+    if not existing:
+        return _resp(404, {"error": "folder not found"})
+    updates = {}
+    for key in ["name", "parent_id"]:
+        if key in body:
+            updates[key] = _str(body[key])
+    if "sort_order" in body:
+        updates["sort_order"] = _int(body["sort_order"])
+    if not updates:
+        return _resp(200, existing[0])
+    ok = db.update("folders", folder_id, updates)
+    if not ok:
+        return _resp(500, {"error": "update failed"})
+    rows = db.query("folders", filters={"id": folder_id}, limit=1)
+    return _resp(200, rows[0] if rows else {})
+
+
+def _delete_folder(folder_id):
+    existing = db.query("folders", filters={"id": folder_id}, limit=1)
+    if not existing:
+        return _resp(404, {"error": "folder not found"})
+    parent_id = _str(existing[0].get("parent_id", ""))
+
+    # reparent child folders to deleted folder's parent
+    children = db.query("folders", filters={"parent_id": folder_id}, limit=500)
+    for child in (children or []):
+        db.update("folders", child["id"], {"parent_id": parent_id})
+
+    # orphan notes in this folder (move to unfiled)
+    notes_in_folder = db.query("notes", filters={"folder_id": folder_id}, limit=1000)
+    for n in (notes_in_folder or []):
+        db.update("notes", n["id"], {"folder_id": ""})
+
+    ok = db.delete("folders", folder_id)
+    if not ok:
+        return _resp(500, {"error": "delete failed"})
+    return _resp(200, {"deleted": True, "orphaned_notes": len(notes_in_folder or [])})
+
+
 # ═══════════════════════════════════════════════
 #  Search
 # ═══════════════════════════════════════════════
@@ -241,6 +358,7 @@ def _get_stats():
     total = 0
     pinned = 0
     archived = 0
+    unfiled = 0
     for n in notes:
         if _int(n.get("archived", 0)) == 1:
             archived = archived + 1
@@ -248,4 +366,8 @@ def _get_stats():
             total = total + 1
             if _int(n.get("pinned", 0)) == 1:
                 pinned = pinned + 1
-    return _resp(200, {"total": total, "pinned": pinned, "archived": archived})
+            if not _str(n.get("folder_id", "")):
+                unfiled = unfiled + 1
+    all_folders = db.query("folders", limit=10000)
+    folder_count = len(all_folders or [])
+    return _resp(200, {"total": total, "pinned": pinned, "archived": archived, "unfiled": unfiled, "folders": folder_count})