docs: comprehensive documentation audit — fix 9 HIGH, 20+ MEDIUM gaps (#4087)

Reference docs fixes:
- cli-commands.md: remove non-existent --provider alibaba, add hermes
  profile/completion/plugins/mcp to top-level table, add --profile/-p
  global flag, add --source chat option
- slash-commands.md: add /yolo and /commands, fix /q alias conflict
  (resolves to /queue not /quit), add missing aliases (/bg, /set-home,
  /reload_mcp, /gateway)
- toolsets-reference.md: fix hermes-api-server (not same as hermes-cli,
  omits clarify/send_message/text_to_speech)
- profile-commands.md: fix show name required not optional, --clone-from
  not --from, add --remove/--name to alias, fix alias path, fix export/
  import arg types, remove non-existent fish completion
- tools-reference.md: add EXA_API_KEY to web tools requires_env
- mcp-config-reference.md: add auth key for OAuth, tool name sanitization
- environment-variables.md: add EXA_API_KEY, update provider values
- plugins.md: remove non-existent ctx.register_command(), add
  ctx.inject_message()

Feature docs additions:
- security.md: add /yolo mode, approval modes (manual/smart/off),
  configurable timeout, expanded dangerous patterns table
- cron.md: add wrap_response config, [SILENT] suppression
- mcp.md: add dynamic tool discovery, MCP sampling support
- cli.md: add Ctrl+Z suspend, busy_input_mode, tool_preview_length
- docker.md: add skills/credential file mounting

Messaging platform docs:
- telegram.md: add webhook mode, DoH fallback IPs
- slack.md: add multi-workspace OAuth support
- discord.md: add DISCORD_IGNORE_NO_MENTION
- matrix.md: add MSC3245 native voice messages
- feishu.md: expand from 129 to 365 lines (encrypt key, verification
  token, group policy, card actions, media, rate limiting, markdown,
  troubleshooting)
- wecom.md: expand from 86 to 264 lines (per-group allowlists, media,
  AES decryption, stream replies, reconnection, troubleshooting)

Configuration docs:
- quickstart.md: add DeepSeek, Copilot, Copilot ACP providers
- configuration.md: add DeepSeek provider, Exa web backend, terminal
  env_passthrough/images, browser.command_timeout, compression params,
  discord config, security/tirith config, timezone, auxiliary models

21 files changed, ~1000 lines added

website/docs/reference/environment-variables.md

@@ -63,7 +63,7 @@ For native Anthropic auth, Hermes prefers Claude Code's own credential files whe
 
 | Variable | Description |
 |----------|-------------|
-| `HERMES_INFERENCE_PROVIDER` | Override provider selection: `auto`, `openrouter`, `nous`, `openai-codex`, `copilot`, `copilot-acp`, `anthropic`, `huggingface`, `zai`, `kimi-coding`, `minimax`, `minimax-cn`, `kilocode`, `alibaba` (default: `auto`) |
+| `HERMES_INFERENCE_PROVIDER` | Override provider selection: `auto`, `openrouter`, `nous`, `openai-codex`, `copilot`, `copilot-acp`, `anthropic`, `huggingface`, `zai`, `kimi-coding`, `minimax`, `minimax-cn`, `kilocode`, `alibaba`, `deepseek`, `opencode-zen`, `opencode-go`, `ai-gateway` (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) |
@@ -80,6 +80,7 @@ For native Anthropic auth, Hermes prefers Claude Code's own credential files whe
 | `FIRECRAWL_API_KEY` | Web scraping ([firecrawl.dev](https://firecrawl.dev/)) |
 | `FIRECRAWL_API_URL` | Custom Firecrawl API endpoint for self-hosted instances (optional) |
 | `TAVILY_API_KEY` | Tavily API key for AI-native web search, extract, and crawl ([app.tavily.com](https://app.tavily.com/home)) |
+| `EXA_API_KEY` | Exa API key for AI-native web search and contents ([exa.ai](https://exa.ai/)) |
 | `BROWSERBASE_API_KEY` | Browser automation ([browserbase.com](https://browserbase.com/)) |
 | `BROWSERBASE_PROJECT_ID` | Browserbase project ID |
 | `BROWSER_USE_API_KEY` | Browser Use cloud browser API key ([browser-use.com](https://browser-use.com/)) |