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.

website/docs/user-guide/features/fallback-providers.md

@@ -47,7 +47,6 @@ Both `provider` and `model` are **required**. If either is missing, the fallback
 
 | Provider | Value | Requirements |
 |----------|-------|-------------|
-| AI Gateway | `ai-gateway` | `AI_GATEWAY_API_KEY` |
 | OpenRouter | `openrouter` | `OPENROUTER_API_KEY` |
 | Nous Portal | `nous` | `hermes setup --portal` (fresh) or `hermes auth add nous` (OAuth) |
 | OpenAI Codex | `openai-codex` | `hermes model` (ChatGPT OAuth) |

website/docs/user-guide/features/tools.md

@@ -65,14 +65,13 @@ The terminal tool can execute commands in different environments:
 | `singularity` | HPC containers | Cluster computing, rootless |
 | `modal` | Cloud execution | Serverless, scale |
 | `daytona` | Cloud sandbox workspace | Persistent remote dev environments |
-| `vercel_sandbox` | Vercel Sandbox cloud microVM | Cloud execution with snapshot-backed filesystem persistence |
 
 ### Configuration
 
 ```yaml
 # In ~/.hermes/config.yaml
 terminal:
-  backend: local    # or: docker, ssh, singularity, modal, daytona, vercel_sandbox
+  backend: local    # or: docker, ssh, singularity, modal, daytona
   cwd: "."          # Working directory
   timeout: 180      # Command timeout in seconds
 ```
@@ -123,41 +122,13 @@ modal setup
 hermes config set terminal.backend modal
 ```
 
-### Vercel Sandbox
-
-```bash
-pip install 'hermes-agent[vercel]'
-hermes config set terminal.backend vercel_sandbox
-hermes config set terminal.vercel_runtime node24
-```
-
-Authenticate with all three of `VERCEL_TOKEN`, `VERCEL_PROJECT_ID`, and `VERCEL_TEAM_ID`. This access-token setup is the supported path for deployments and normal long-running Hermes processes on Render, Railway, Docker, and similar hosts. Supported runtimes are `node24`, `node22`, and `python3.13`; Hermes defaults to `/vercel/sandbox` as the remote workspace root.
-
-For one-off local development, Hermes also accepts short-lived Vercel OIDC tokens:
-
-```bash
-VERCEL_OIDC_TOKEN="$(vc project token <project-name>)" hermes chat
-```
-
-From a linked Vercel project directory:
-
-```bash
-VERCEL_OIDC_TOKEN="$(vc project token)" hermes chat
-```
-
-With `container_persistent: true`, Hermes uses Vercel snapshots to preserve filesystem state across sandbox recreation for the same task. This can include Hermes-synced credentials, skills, and cache files inside the sandbox. Snapshots do not preserve live processes, PID space, or the same live sandbox identity.
-
-Background terminal commands use Hermes' generic non-local process flow: spawn, poll, wait, log, and kill work through the normal process tool while the sandbox is alive, but Hermes does not provide native Vercel detached-process recovery after cleanup or restart.
-
-Leave `container_disk` unset or at the shared default `51200`; custom disk sizing is unsupported for Vercel Sandbox and will fail diagnostics/backend creation.
-
 ### Container Resources
 
 Configure CPU, memory, disk, and persistence for all container backends:
 
 ```yaml
 terminal:
-  backend: docker  # or singularity, modal, daytona, vercel_sandbox
+  backend: docker  # or singularity, modal, daytona
   container_cpu: 1              # CPU cores (default: 1)
   container_memory: 5120        # Memory in MB (default: 5GB)
   container_disk: 51200         # Disk in MB (default: 50GB)