remove Vercel AI Gateway and Vercel Sandbox (#33067)

* remove Vercel AI Gateway provider and Vercel Sandbox terminal backend

Both Vercel-hosted integrations are removed end-to-end. Users on the AI
Gateway should switch to OpenRouter or one of the other aggregators
(Nous Portal, Kilo Code). Users on the Vercel Sandbox backend should
switch to Docker, Modal, Daytona, or SSH.

What's removed:
- `plugins/model-providers/ai-gateway/` provider plugin
- `hermes_cli/vercel_auth.py` Vercel-Sandbox auth helper
- `tools/environments/vercel_sandbox.py` terminal backend
- `ai-gateway` provider wiring across auth, doctor, setup, models,
  config, status, providers, main, web_server, model_normalize, dump
- `vercel_sandbox` backend wiring across terminal_tool, file_tools,
  code_execution_tool, file_operations, approval, skills_tool,
  environments/local, credential_files, lazy_deps, prompt_builder,
  cli, gateway/run
- `AI_GATEWAY_BASE_URL` constant, `_AI_GATEWAY_HEADERS` auxiliary-client
  header set, run_agent base-URL header/reasoning special-cases
- `[vercel]` pyproject extra and `vercel`/`vercel-workers` from uv.lock
- env vars: `AI_GATEWAY_API_KEY`, `AI_GATEWAY_BASE_URL`, `VERCEL_TOKEN`,
  `VERCEL_PROJECT_ID`, `VERCEL_TEAM_ID`, `VERCEL_OIDC_TOKEN`,
  `TERMINAL_VERCEL_RUNTIME`
- Tests: deletes test_ai_gateway_models.py and
  test_vercel_sandbox_environment.py; scrubs references across 23
  surviving test files (no entire tests deleted unless they were
  dedicated to AI Gateway / Sandbox)
- Docs: provider tables, env-var reference, setup guides, security
  notes, tool config, terminal-backend tables — English plus zh-Hans
  i18n parity
- `hermes-agent` skill: provider table entry and remote-backend list

What stays (intentional):
- `popular-web-designs/templates/vercel.md` — CSS design reference,
  unrelated to Vercel-the-AI-product
- `x-vercel-id` in `stream_diag.py` headers — generic Vercel CDN
  response header, useful diag signal on any Vercel-hosted endpoint
- `vercel-labs/agent-browser` URL in browser config — lightpanda
  browser project, different OSS effort
- `userStories.json` historical contributor entry mentioning Vercel
  Sandbox — archive, not active docs

Validation:
- 1153 tests in the 22 targeted files pass (`scripts/run_tests.sh`)
- Full repo `py_compile` clean
- Live import of every touched module + invariant check (no
  `ai-gateway` in `PROVIDER_REGISTRY`, no `_AI_GATEWAY_HEADERS`, no
  `vercel_sandbox` in `_REMOTE_TERMINAL_BACKENDS`)

* test: convert profile-count check from change-detector to invariant

The hardcoded "== 34" assertion broke when ai-gateway was removed.
Per AGENTS.md change-detector-test guidance, assert the relationship
(registry count >= number of plugin dirs) instead of a literal count.
Counts shift when providers are added/removed; that's expected.

tests/hermes_cli/test_setup.py

@@ -30,17 +30,6 @@ def _clear_provider_env(monkeypatch):
         monkeypatch.delenv(key, raising=False)
 
 
-def _clear_vercel_env(monkeypatch):
-    for key in (
-        "TERMINAL_VERCEL_RUNTIME",
-        "VERCEL_OIDC_TOKEN",
-        "VERCEL_TOKEN",
-        "VERCEL_PROJECT_ID",
-        "VERCEL_TEAM_ID",
-    ):
-        monkeypatch.delenv(key, raising=False)
-
-
 def _stub_tts(monkeypatch):
     """Stub out TTS prompts so setup_model_provider doesn't block."""
     monkeypatch.setattr("hermes_cli.setup.prompt_choice", lambda q, c, d=0: (
@@ -494,85 +483,6 @@ def test_modal_setup_persists_direct_mode_when_user_chooses_their_own_account(tm
     assert config["terminal"]["modal_mode"] == "direct"
 
 
-def test_vercel_setup_configures_access_token_auth(tmp_path, monkeypatch):
-    monkeypatch.setenv("HERMES_HOME", str(tmp_path))
-    _clear_vercel_env(monkeypatch)
-    monkeypatch.setenv("VERCEL_OIDC_TOKEN", "old-oidc")
-    monkeypatch.setitem(sys.modules, "vercel", types.ModuleType("vercel"))
-    config = load_config()
-
-    def fake_prompt_choice(question, choices, default=0):
-        if question == "Select terminal backend:":
-            return 5
-        raise AssertionError(f"Unexpected prompt_choice call: {question}")
-
-    prompt_values = iter(["python3.13", "yes", "2", "4096", "token", "project", "team"])
-
-    monkeypatch.setattr("hermes_cli.setup.prompt_choice", fake_prompt_choice)
-    monkeypatch.setattr("hermes_cli.setup.prompt", lambda *args, **kwargs: next(prompt_values))
-
-    from hermes_cli.setup import setup_terminal_backend
-
-    setup_terminal_backend(config)
-
-    assert config["terminal"]["backend"] == "vercel_sandbox"
-    assert config["terminal"]["vercel_runtime"] == "python3.13"
-    assert config["terminal"]["container_disk"] == 51200
-    assert os.environ["TERMINAL_VERCEL_RUNTIME"] == "python3.13"
-    assert "VERCEL_OIDC_TOKEN" not in os.environ
-    assert os.environ["VERCEL_TOKEN"] == "token"
-    assert os.environ["VERCEL_PROJECT_ID"] == "project"
-    assert os.environ["VERCEL_TEAM_ID"] == "team"
-
-
-def test_vercel_setup_prefills_project_and_team_from_link_file(tmp_path, monkeypatch):
-    monkeypatch.setenv("HERMES_HOME", str(tmp_path))
-    _clear_vercel_env(monkeypatch)
-    project_root = tmp_path / "project"
-    nested = project_root / "app" / "src"
-    nested.mkdir(parents=True)
-    vercel_dir = project_root / ".vercel"
-    vercel_dir.mkdir()
-    (vercel_dir / "project.json").write_text(
-        json.dumps({"projectId": "linked-project", "orgId": "linked-team"}),
-        encoding="utf-8",
-    )
-    monkeypatch.chdir(nested)
-    monkeypatch.setitem(sys.modules, "vercel", types.ModuleType("vercel"))
-    config = load_config()
-    config["terminal"]["container_disk"] = 999
-
-    def fake_prompt_choice(question, choices, default=0):
-        if question == "Select terminal backend:":
-            return 5
-        raise AssertionError(f"Unexpected prompt_choice call: {question}")
-
-    prompt_values = iter(["node24", "no", "1", "5120", "token", "", ""])
-    defaults = {}
-
-    def fake_prompt(message, default="", **kwargs):
-        defaults[message] = default
-        value = next(prompt_values)
-        return value or default
-
-    monkeypatch.setattr("hermes_cli.setup.prompt_choice", fake_prompt_choice)
-    monkeypatch.setattr("hermes_cli.setup.prompt", fake_prompt)
-
-    from hermes_cli.setup import setup_terminal_backend
-
-    setup_terminal_backend(config)
-
-    assert config["terminal"]["backend"] == "vercel_sandbox"
-    assert config["terminal"]["container_persistent"] is False
-    assert config["terminal"]["container_disk"] == 51200
-    assert "VERCEL_OIDC_TOKEN" not in os.environ
-    assert os.environ["VERCEL_TOKEN"] == "token"
-    assert os.environ["VERCEL_PROJECT_ID"] == "linked-project"
-    assert os.environ["VERCEL_TEAM_ID"] == "linked-team"
-    assert defaults["    Vercel project ID"] == "linked-project"
-    assert defaults["    Vercel team ID"] == "linked-team"
-
-
 def test_setup_slack_saves_home_channel(monkeypatch):
     """_setup_slack() saves SLACK_HOME_CHANNEL when the user provides one."""
     saved = {}