fix(docs): replace dead gnubok.app domain with app.gnubok.se across public docs (#683)

gnubok.app has no DNS delegation (the .app TLD returns no NS records for
it), so every https://gnubok.app/... link in the public docs was dead —
including the OAuth connector URL a Claude Connectors Directory reviewer
would paste from the new Connect-with-Claude page (#682), and the docs
links in the gnubok-mcp npm README that ships in the tarball.

app.gnubok.se is the live production domain (the MCP endpoint there
correctly answers 401 unauthenticated) and was already the default
GNUBOK_URL in the npm bridge and the branding-service appUrl fallback.

Mechanical swap: 55 occurrences across 11 files, all https:// URL form
(verified no emails or identifiers). Docs content only — no code paths.
Also resolves the greptile domain-mismatch finding on #682.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/docs/content/errors.ts

@@ -88,7 +88,7 @@ export function buildErrorReferenceMd(): string {
   lines.push('      "tool": "fiscal_periods.unlock"')
   lines.push('    },')
   lines.push('    "details": { "fiscal_period_id": "..." },')
-  lines.push('    "docs_url": "https://gnubok.app/docs/api/errors#period_locked"')
+  lines.push('    "docs_url": "https://app.gnubok.se/docs/api/errors#period_locked"')
   lines.push('  },')
   lines.push('  "meta": { "request_id": "req_...", "api_version": "..." }')
   lines.push('}')