docs: comprehensive update for recent merged PRs (#9019)

Audit and update documentation across 12 files to match changes from
~50 recently merged PRs. Key updates:

Slash commands (slash-commands.md):
- Add 5 missing commands: /snapshot, /fast, /image, /debug, /restart
- Fix /status incorrectly labeled as messaging-only (available in both)
- Add --global flag to /model docs
- Add [focus topic] arg to /compress docs

CLI commands (cli-commands.md):
- Add hermes debug share section with options and examples
- Add hermes backup section with --quick and --label flags
- Add hermes import section

Feature docs:
- TTS: document global tts.speed and per-provider speed for Edge/OpenAI
- Web dashboard: add docs for 5 missing pages (Sessions, Logs,
  Analytics, Cron, Skills) and 15+ API endpoints
- WhatsApp: add streaming, 4K chunking, and markdown formatting docs
- Skills: add GitHub rate-limit/GITHUB_TOKEN troubleshooting tip
- Budget: document CLI notification on iteration budget exhaustion

Config migration (compression.summary_* → auxiliary.compression.*):
- Update configuration.md, environment-variables.md,
  fallback-providers.md, cli.md, and context-compression-and-caching.md
- Replace legacy compression.summary_model/provider/base_url references
  with auxiliary.compression.model/provider/base_url
- Add legacy migration info boxes explaining auto-migration

Minor fixes:
- wecom-callback.md: clarify 'text only' limitation (input only)
- Escape {session_id}/{job_id} in web-dashboard.md headings for MDX

website/docs/user-guide/messaging/wecom-callback.md

@@ -143,5 +143,5 @@ The crypto implementation is compatible with Tencent's official WXBizMsgCrypt SD
 
 - **No streaming** — replies arrive as complete messages after the agent finishes
 - **No typing indicators** — the callback model doesn't support typing status
-- **Text only** — currently supports text messages; image/file/voice not yet implemented
+- **Text only** — currently supports text messages for input; image/file/voice input not yet implemented. The agent is aware of outbound media capabilities via the WeCom platform hint (images, documents, video, voice).
 - **Response latency** — agent sessions take 3–30 minutes; users see the reply when processing completes