fix: workspace delete MissingGreenlet + nginx cache-busting

- Convert WorkspaceHasInstancesError to store plain dicts instead of
  SQLAlchemy ORM objects, preventing lazy-load failures outside async
  session context (MissingGreenlet)
- Update both delete endpoints (top-level and nested) to use exc.instances
  directly since they're already plain dicts
- Add no-cache headers for index.html in nginx.conf so browsers always
  fetch new hashed JS/CSS bundles on deploy

apps/api/src/api/workspaces.py

@@ -91,7 +91,7 @@ async def delete_workspace_top_level(
             status_code=409,
             detail={
                 "message": "Workspace has running tool instances",
-                "instances": [{"id": str(i.id), "name": i.name} for i in exc.instances],
+                "instances": exc.instances,
             },
         ) from exc
     except Exception as exc:
@@ -358,7 +358,7 @@ async def delete_workspace(
             status_code=409,
             detail={
                 "message": "Workspace has running tool instances",
-                "instances": [{"id": str(i.id), "name": i.name} for i in exc.instances],
+                "instances": exc.instances,
             },
         ) from exc
     except Exception as exc:

apps/api/src/services/workspace_manager.py

@@ -37,7 +37,7 @@ class SyncResult:
 class WorkspaceHasInstancesError(Exception):
     """Raised when attempting to delete a workspace with running instances."""
 
-    def __init__(self, instances: list[ToolInstance]) -> None:
+    def __init__(self, instances: list[dict]) -> None:
         self.instances = instances
         super().__init__(f"Workspace has {len(instances)} running tool instance(s)")
 
@@ -139,7 +139,9 @@ class WorkspaceManager:
 
         instances = await self._get_instances(workspace, session)
         if instances and not force:
-            raise WorkspaceHasInstancesError(instances)
+            raise WorkspaceHasInstancesError(
+                [{"id": str(i.id), "name": i.name} for i in instances]
+            )
 
         # Stop and delete all instances
         for instance in instances:

apps/web/nginx.conf

@@ -15,6 +15,12 @@ server {
         try_files $uri $uri/ /index.html;
     }
 
+    # Never cache index.html so browsers always fetch new hashed JS/CSS
+    location = /index.html {
+        add_header Cache-Control "no-cache, no-store, must-revalidate";
+        add_header Pragma "no-cache";
+    }
+
     # Cache static assets
     location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2)$ {
         expires 1y;