fix: login → /workspaces, workspace tree filtered, sidebar CRUD

- Login redirect (all modes) now goes to /workspaces
- Workspace tree API filters by active workspace_id (no leak)
- Workspace name in sidebar from cookie (active_ws_name)
- Sidebar workspace section: 📄 new page + 📁 new folder buttons
- deleteWorkspacePage() in sidebar with confirmation
- _load_workspace_pages() helper with workspace_id filter
- CSS for sidebar-item-delete button (× on hover)

app/routers/dashboard.py

@@ -482,10 +482,13 @@ async def local_workspace_page(request: Request):
     if not user:
         return RedirectResponse("/auth/login?provider=local", status_code=302)
 
+    ws = _get_active_workspace(request)
+    ws_id = ws["id"] if ws else None
     with get_conn() as conn:
         rows = conn.execute(
-            "SELECT id, title FROM pages WHERE parent_id IS NULL ORDER BY created_at DESC"
-        ).fetchall()
+            "SELECT id, title FROM pages WHERE parent_id IS NULL AND workspace_id=? ORDER BY created_at DESC",
+            (ws_id,),
+        ).fetchall() if ws_id else []
     items = [{"id": r["id"], "name": r["title"] or "Untitled", "type": "page"} for r in rows]
 
     ctx = {**sidebar, "user": user, "workspace_name": sidebar.get("active_ws_name", "My Workspace"), "items": items}
@@ -495,11 +498,14 @@ async def local_workspace_page(request: Request):
 
 @router.get("/api/local-workspace/tree")
 async def local_workspace_tree(request: Request):
-    """Return the file/folder tree."""
+    """Return the file/folder tree filtered by active workspace."""
+    ws = _get_active_workspace(request)
+    ws_id = ws["id"] if ws else None
     with get_conn() as conn:
         roots = conn.execute(
-            "SELECT id, title FROM pages WHERE parent_id IS NULL ORDER BY created_at DESC"
-        ).fetchall()
+            "SELECT id, title FROM pages WHERE parent_id IS NULL AND workspace_id=? ORDER BY created_at DESC",
+            (ws_id,),
+        ).fetchall() if ws_id else []
     tree = []
     for r in roots:
         with get_conn() as conn: