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/reference/environment-variables.md

@@ -328,17 +328,24 @@ For cloud sandbox backends, persistence is filesystem-oriented. `TERMINAL_LIFETI
 
 ## Context Compression (config.yaml only)
 
-Context compression is configured exclusively through the `compression` section in `config.yaml` — there are no environment variables for it.
+Context compression is configured exclusively through `config.yaml` — there are no environment variables for it. Threshold settings live in the `compression:` block, while the summarization model/provider lives under `auxiliary.compression:`.
 
 ```yaml
 compression:
   enabled: true
   threshold: 0.50
-  summary_model: ""                            # empty = use main configured model
-  summary_provider: auto
-  summary_base_url: null  # Custom OpenAI-compatible endpoint for summaries
+
+auxiliary:
+  compression:
+    model: ""                                  # empty = auto-detect
+    provider: auto
+    base_url: null                             # Custom OpenAI-compatible endpoint for summaries
 ```
 
+:::info Legacy migration
+Older configs with `compression.summary_model`, `compression.summary_provider`, and `compression.summary_base_url` are automatically migrated to `auxiliary.compression.*` on first load.
+:::
+
 ## Auxiliary Task Overrides
 
 | Variable | Description |