feat: add z.ai/GLM, Kimi/Moonshot, MiniMax as first-class providers

Adds 4 new direct API-key providers (zai, kimi-coding, minimax, minimax-cn)
to the inference provider system. All use standard OpenAI-compatible
chat/completions endpoints with Bearer token auth.

Core changes:
- auth.py: Extended ProviderConfig with api_key_env_vars and base_url_env_var
  fields. Added providers to PROVIDER_REGISTRY. Added provider aliases
  (glm, z-ai, zhipu, kimi, moonshot). Added auto-detection of API-key
  providers in resolve_provider(). Added resolve_api_key_provider_credentials()
  and get_api_key_provider_status() helpers.
- runtime_provider.py: Added generic API-key provider branch in
  resolve_runtime_provider() — any provider with auth_type='api_key'
  is automatically handled.
- main.py: Added providers to hermes model menu with generic
  _model_flow_api_key_provider() flow. Updated _has_any_provider_configured()
  to check all provider env vars. Updated argparse --provider choices.
- setup.py: Added providers to setup wizard with API key prompts and
  curated model lists.
- config.py: Added env vars (GLM_API_KEY, KIMI_API_KEY, MINIMAX_API_KEY,
  etc.) to OPTIONAL_ENV_VARS.
- status.py: Added API key display and provider status section.
- doctor.py: Added connectivity checks for each provider endpoint.
- cli.py: Updated provider docstrings.

Docs: Updated README.md, .env.example, cli-config.yaml.example,
cli-commands.md, environment-variables.md, configuration.md.

Tests: 50 new tests covering registry, aliases, resolution, auto-detection,
credential resolution, and runtime provider dispatch.

Inspired by PR #33 (numman-ali) which proposed a provider registry approach.
Credit to tars90percent (PR #473) and manuelschipper (PR #420) for related
provider improvements merged earlier in this changeset.

website/docs/reference/environment-variables.md

@@ -15,6 +15,14 @@ All variables go in `~/.hermes/.env`. You can also set them with `hermes config
 | `OPENROUTER_API_KEY` | OpenRouter API key (recommended for flexibility) |
 | `OPENAI_API_KEY` | API key for custom OpenAI-compatible endpoints (used with `OPENAI_BASE_URL`) |
 | `OPENAI_BASE_URL` | Base URL for custom endpoint (VLLM, SGLang, etc.) |
+| `GLM_API_KEY` | z.ai / ZhipuAI GLM API key ([z.ai](https://z.ai)) |
+| `GLM_BASE_URL` | Override z.ai base URL (default: `https://api.z.ai/api/paas/v4`) |
+| `KIMI_API_KEY` | Kimi / Moonshot AI API key ([moonshot.ai](https://platform.moonshot.ai)) |
+| `KIMI_BASE_URL` | Override Kimi base URL (default: `https://api.moonshot.ai/v1`) |
+| `MINIMAX_API_KEY` | MiniMax API key — global endpoint ([minimax.io](https://www.minimax.io)) |
+| `MINIMAX_BASE_URL` | Override MiniMax base URL (default: `https://api.minimax.io/v1`) |
+| `MINIMAX_CN_API_KEY` | MiniMax API key — China endpoint ([minimaxi.com](https://www.minimaxi.com)) |
+| `MINIMAX_CN_BASE_URL` | Override MiniMax China base URL (default: `https://api.minimaxi.com/v1`) |
 | `HERMES_MODEL` | Preferred model name (checked before `LLM_MODEL`, used by gateway) |
 | `LLM_MODEL` | Default model name (fallback when not set in config.yaml) |
 | `VOICE_TOOLS_OPENAI_KEY` | OpenAI key for TTS and voice transcription (separate from custom endpoint) |
@@ -24,7 +32,7 @@ All variables go in `~/.hermes/.env`. You can also set them with `hermes config
 
 | Variable | Description |
 |----------|-------------|
-| `HERMES_INFERENCE_PROVIDER` | Override provider selection: `auto`, `openrouter`, `nous` (default: `auto`) |
+| `HERMES_INFERENCE_PROVIDER` | Override provider selection: `auto`, `openrouter`, `nous`, `zai`, `kimi-coding`, `minimax`, `minimax-cn` (default: `auto`) |
 | `HERMES_PORTAL_BASE_URL` | Override Nous Portal URL (for development/testing) |
 | `NOUS_INFERENCE_BASE_URL` | Override Nous inference API URL |
 | `HERMES_NOUS_MIN_KEY_TTL_SECONDS` | Min agent key TTL before re-mint (default: 1800 = 30min) |