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/user-guide/messaging/discord.md

@@ -19,6 +19,7 @@ Before setup, here's the part most people want to know: how Hermes behaves once
 | **Free-response channels** | You can make specific channels mention-free with `DISCORD_FREE_RESPONSE_CHANNELS`, or disable mentions globally with `DISCORD_REQUIRE_MENTION=false`. |
 | **Threads** | Hermes replies in the same thread. Mention rules still apply unless that thread or its parent channel is configured as free-response. Threads stay isolated from the parent channel for session history. |
 | **Shared channels with multiple users** | By default, Hermes isolates session history per user inside the channel for safety and clarity. Two people talking in the same channel do not share one transcript unless you explicitly disable that. |
+| **Messages mentioning other users** | When `DISCORD_IGNORE_NO_MENTION` is `true` (the default), Hermes stays silent if a message @mentions other users but does **not** mention the bot. This prevents the bot from jumping into conversations directed at other people. Set to `false` if you want the bot to respond to all messages regardless of who is mentioned. This only applies in server channels, not DMs. |
 
 :::tip
 If you want a normal bot-help channel where people can talk to Hermes without tagging it every time, add that channel to `DISCORD_FREE_RESPONSE_CHANNELS`.
@@ -253,6 +254,9 @@ DISCORD_ALLOWED_USERS=284102345871466496
 
 # Optional: channels where bot responds without @mention (comma-separated channel IDs)
 # DISCORD_FREE_RESPONSE_CHANNELS=1234567890,9876543210
+
+# Optional: ignore messages that @mention other users but NOT the bot (default: true)
+# DISCORD_IGNORE_NO_MENTION=true
 ```
 
 Optional behavior settings in `~/.hermes/config.yaml`: