docs(api): correct /docs/api against the v1 implementation (#999)

Audited every endpoint, param, header, request/response field, error code, and
webhook event in the public API docs against the v1 implementation and fixed the
drift; addressed two rounds of CodeRabbit review.

- Error envelope, idempotency, dry-run, and reversal-field corrections.
- Registered the missing articles/dimensions/inbox-items reference resources.
- Cookbook fixes: removed nonexistent endpoints, corrected params/fields, fixed
  the test-key vs live-key quickstart flow and the year-end lock/close sequence.
- Webhooks/changelog: retry window ~87h (incl. route metadata), shipped-vs-
  coming-soon, counts, API-key format, previous_attributes.
- export-docs-to-website.mts absolutises app-served links for the website.

The gnubok-website side is on branch docs/api-correctness (already deployed).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

lib/webhooks/dispatcher.ts

@@ -28,7 +28,7 @@ import { createLogger } from '@/lib/logger'
 
 const log = createLogger('webhooks/dispatcher')
 
-/** 7 retries over ~72h. Index = attempts BEFORE this one. */
+/** 7 retries over ~87h (≈3.6 days). Index = attempts BEFORE this one. */
 const RETRY_BACKOFF_SECONDS: ReadonlyArray<number> = [
   60,        //  1m: first retry
   5 * 60,    //  5m