docs: 30-day overhaul — correctness audit, PR coverage, Nous Portal weave, sidebar reorg (#33782)

* docs(audit): correctness pass across getting-started, reference, features, messaging, developer-guide, guides, integrations, user-guide

* docs: add PR coverage for last 30d + Nous Portal weave + nav reorg + build fixes

- Add docs for top user-visible PRs that shipped without docs (api-server
  session control, kanban features, telegram pin/edit, provider client tag,
  xAI retired-model migration, cron name lookup, --branch update flag, etc.)
- Apply Nous Portal weave across 23 pages (tasteful one-liners on
  getting-started/learning-path, configuration, overview, vision, x-search,
  credential-pools, provider-routing, cron, codex-runtime, profiles, docker,
  messaging/index, multiple guides, plus FAQ + index promotion)
- Reorganize sidebar: split Messaging into Popular/M365/Chinese/Other,
  Reference into Command/Configuration/Tools-Skills sub-categories, add
  orphan developer-guide pages (web-search-provider-plugin,
  browser-supervisor), move features from Integrations back to Features,
  fold lone spotify into Media & Web.
- Regenerate skill stubs + catalogs (kanban-codex-lane, hermes-s6-container-
  supervision, web-pentest)
- Fix broken anchor links (security/cron, configuration/fallback, telegram
  large-files, adding-platform-adapters step-by-step)

website/docs/developer-guide/provider-runtime.md

@@ -193,7 +193,11 @@ Cron jobs **do** support fallback: `run_job()` reads `fallback_providers` (or le
 
 ### Test coverage
 
-See `tests/test_fallback_model.py` for comprehensive tests covering all supported providers, one-shot semantics, and edge cases.
+Fallback behavior is exercised across several suites:
+
+- `tests/run_agent/test_fallback_credential_isolation.py` — credential isolation between primary and fallback
+- `tests/hermes_cli/test_fallback_cmd.py` — the `/fallback` CLI command
+- `tests/gateway/test_fallback_eviction.py` — gateway eviction of failed providers
 
 ## Related docs