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/web/src/pages/workspaces.tsx

@@ -18,12 +18,7 @@ export function WorkspacesPage() {
 	const actions = useWorkspaceActions();
 
 	const handleDelete = async (workspace: Workspace) => {
-		await actions.delete(
-			workspace.project_id,
-			workspace.repo_id,
-			workspace,
-			refresh,
-		);
+		await actions.delete(workspace, refresh);
 	};
 
 	const handleSync = async (workspace: Workspace) => {