docs(auth): replace stale 'hermes login' references with 'hermes auth add'

'hermes login' was removed (the command now just prints a deprecation
message and exits). The bundled hermes-agent SKILL.md, in-code error
messages, the tip rotation, the proxy adapters, and the docs site
still pointed agents and users at the dead command — so models loading
the skill kept running 'hermes login --provider openai-codex' and
getting a dead-end print.

Replacements use the canonical 'hermes auth add <provider>' surface
(or bare 'hermes auth' for the interactive manager).

Files:
- skills/autonomous-ai-agents/hermes-agent/SKILL.md (+ regenerated docs page)
- hermes_cli/tips.py (tip rotation)
- agent/google_oauth.py (gemini-cli error message)
- agent/conversation_loop.py (nous re-auth troubleshooting line)
- agent/credential_sources.py (docstring)
- hermes_cli/proxy/cli.py + hermes_cli/proxy/adapters/nous_portal.py (proxy auth hints)
- tests/hermes_cli/test_proxy.py (updated assertions)
- website/docs/reference/faq.md, website/docs/user-guide/features/subscription-proxy.md
- zh-Hans i18n mirrors for the above

'hermes logout' is still a live command and is left untouched.
The 'hermes login' stub in hermes_cli/auth.py:login_command() and
the cli-commands.md 'Deprecated' rows are intentionally kept as
the discoverable deprecation surface.

website/i18n/zh-Hans/docusaurus-plugin-content-docs/current/reference/faq.md

@@ -19,7 +19,7 @@ Hermes Agent 可与任何兼容 OpenAI 的 API 配合使用。支持的提供商
 - **[OpenRouter](https://openrouter.ai/)** — 通过一个 API key 访问数百个模型（推荐，灵活性强）
 - **Nous Portal** — Nous Research 自有推理端点
 - **OpenAI** — GPT-5.4、GPT-5-codex、GPT-4.1、GPT-4o 等
-- **Anthropic** — Claude 模型（直接 API、通过 `hermes login anthropic` 进行 OAuth、OpenRouter 或任何兼容代理）
+- **Anthropic** — Claude 模型（直接 API、通过 `hermes auth add anthropic` 进行 OAuth、OpenRouter 或任何兼容代理）
 - **Google** — Gemini 模型（通过 `gemini` 提供商直接调用 API、`google-gemini-cli` OAuth 提供商、OpenRouter 或兼容代理）
 - **z.ai / ZhipuAI** — GLM 模型
 - **Kimi / Moonshot AI** — Kimi 模型