fix(serve): sync E2E baseline capabilities with registry (#4284)

PRs #4249 (workspace memory + agents CRUD) and #4269 (workspace file
read routes) added `workspace_memory`, `workspace_agents`, and
`workspace_file_read` to `SERVE_CAPABILITY_REGISTRY` and updated the
unit-level `EXPECTED_STAGE1_FEATURES` in
`packages/cli/src/serve/server.test.ts`, but missed the matching
integration-test expectation. The E2E `qwen serve — capabilities
envelope > advertises all baseline capabilities` assertion has been
failing on `main` since those PRs landed.

Append the three tags in the same positions as
`SERVE_CAPABILITY_REGISTRY` and the unit-level constant
(`workspace_memory` + `workspace_agents` after `workspace_providers`,
`workspace_file_read` after `mcp_guardrails`). No production code
changes — same shape as #4268.

Author: doudouOUC

integration-tests/cli/qwen-serve-routes.test.ts

@@ -208,13 +208,16 @@ describe('qwen serve — capabilities envelope', () => {
       'workspace_mcp',
       'workspace_skills',
       'workspace_providers',
+      'workspace_memory',
+      'workspace_agents',
       'workspace_env',
       'workspace_preflight',
       'session_context',
       'session_supported_commands',
       'session_close',
       'session_metadata',
       'mcp_guardrails',
+      'workspace_file_read',
     ]);
   });
 });