fix: workspace delete mixed-content error via top-level endpoint

- Add top-level DELETE /workspaces/{workspace_id} endpoint (avoids nested path)
- Frontend deleteWorkspace now uses /workspaces/{id}/?force=... (no project/repo needed)
- Update useWorkspaceActions, ProjectsPage, WorkspacesPage to match new signature

Quality gates: ruff clean, tsc --noEmit clean, pytest workspaces API (9 passed, 1 skipped)

apps/api/src/api/workspaces.py

@@ -67,6 +67,41 @@ async def list_all_workspaces(
     ]
 
 
+@all_workspaces_router.delete("/{workspace_id}")
+async def delete_workspace_top_level(
+    workspace_id: uuid.UUID,
+    force: bool = Query(False),
+    user_id: uuid.UUID = Depends(get_current_user_id),
+    session: AsyncSession = Depends(get_db_session),
+) -> dict:
+    """Delete a workspace via top-level path."""
+    workspace = await session.get(Workspace, workspace_id)
+    if not workspace or workspace.user_id != user_id:
+        raise HTTPException(status_code=404, detail="Workspace not found")
+
+    manager = WorkspaceManager()
+    try:
+        await manager.delete(workspace, force=force, session=session)
+        await session.commit()
+    except WorkspaceHasInstancesError as exc:
+        await session.rollback()
+        raise HTTPException(
+            status_code=409,
+            detail={
+                "message": "Workspace has running tool instances",
+                "instances": [{"id": str(i.id), "name": i.name} for i in exc.instances],
+            },
+        ) from exc
+    except Exception as exc:
+        await session.rollback()
+        logger.error("Failed to delete workspace: %s", exc)
+        raise HTTPException(
+            status_code=500, detail="Failed to delete workspace"
+        ) from exc
+
+    return {"status": "deleted"}
+
+
 @all_workspaces_router.post("/")
 async def create_workspace_top_level(
     data: dict,