feat(reports): gate unbuilt Marketing report to 404 for beta

Sales/Operational/Financial are built + verified; Marketing is blocked
on the website cutover (launch-readiness Init 1b), not on code. Rather
than hide the whole reports surface behind a module toggle, keep it live
for beta and 404 the one unbuilt kind so a hand-typed /reports/marketing
URL can't reach the "in development" placeholder. The landing page
already advertises only the three live reports + Custom.

Remove the UNAVAILABLE_NEW_KINDS entry when the Marketing report ships.

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

docs/launch-readiness.md

@@ -50,6 +50,16 @@ Phases (status snapshot 2026-05-27):
    PDF; server-side PDF endpoint for branded output. _See gaps
    below._
 3. ❌ Marketing report — NOT BUILT. Pending Init 1b cutover.
+   **Beta gate (2026-06-02):** the `marketing` kind in
+   `reports/[kind]/page.tsx` now returns `notFound()` (via
+   `UNAVAILABLE_NEW_KINDS`) instead of the "in development" placeholder,
+   so the beta reports surface reads as complete — the landing page only
+   advertises Sales / Operational / Financial / Custom, and the
+   hand-typed `/reports/marketing` URL 404s. **Remove the
+   `UNAVAILABLE_NEW_KINDS` entry when this report ships.** Decision: keep
+   the reports page live for beta rather than hiding it behind a module
+   toggle — 3 of 4 reports are fully built + verified (export, templates,
+   scheduling) and strictly beat the dashboard-only fallback.
 4. ✅ Financial report — **SHIPPED in b690fb8d.** Built on the canonical
    payments + expenses tables (invoices module stays OFF); the
    invoice-centric spec was reframed onto the payments model