fix(tests): resolve CI test failures — pool auto-seeding, stale assertions, mock isolation

Salvaged from PR #10643 by kshitijk4poor, updated for current main.

Root causes fixed:
1. Telegram xdist mock pollution — new tests/gateway/conftest.py with shared
   mock that runs at collection time (prevents ChatType=None caching)
2. VIRTUAL_ENV env var leak — monkeypatch.delenv in _detect_venv_dir tests
3. Copilot base_url missing — add fallback in _resolve_runtime_from_pool_entry
4. Stale vision model assertion — zai now uses glm-5v-turbo
5. Reasoning item id intentionally stripped — assert 'id' not in (store=False)
6. Context length warning unreachable — pass base_url to AIAgent in test
7. Kimi provider label updated — 'Kimi / Kimi Coding Plan' matches models.py
8. Google Workspace calendar tests — rewritten for current production code,
   properly mock subprocess on api_module, removed stale +agenda assertions
9. Credential pool auto-seeding — mock _select_pool_entry / _resolve_auto /
   _import_codex_cli_tokens to prevent real credentials from leaking into tests

tests/agent/test_credential_pool.py

@@ -252,6 +252,11 @@ def test_exhausted_402_entry_resets_after_one_hour(tmp_path, monkeypatch):
 
 def test_explicit_reset_timestamp_overrides_default_429_ttl(tmp_path, monkeypatch):
     monkeypatch.setenv("HERMES_HOME", str(tmp_path / "hermes"))
+    # Prevent auto-seeding from Codex CLI tokens on the host
+    monkeypatch.setattr(
+        "hermes_cli.auth._import_codex_cli_tokens",
+        lambda: None,
+    )
     _write_auth_store(
         tmp_path,
         {