feat(berths): public berths API + health env-match endpoint

Adds the read-only public-website data feed promised by plan §4.5 and
§7.3. The marketing site's `getBerths()` swap is now a one-line URL
change against the existing 5-min TTL behaviour.

- src/app/api/public/berths/route.ts: GET / unauth, returns the full
  port-nimara berth list as { list, pageInfo } in the verbatim NocoDB
  shape ("Mooring Number", "Side Pontoon", quoted-key fields). Cache:
  s-maxage=300 + stale-while-revalidate=60. portSlug query param lets
  future ports opt in.
- src/app/api/public/berths/[mooringNumber]/route.ts: GET single. Up-
  front regex validation (^[A-Z]+\\d+$) rejects malformed lookups with
  400 + cache-control:no-store before hitting the DB. 404 + no-store
  when not found.
- src/app/api/public/health/route.ts: returns { status, env, appUrl,
  timestamp } so the marketing site can refuse to start when its
  CRM_PUBLIC_URL points at a different deployment env (§14.8 critical
  env-mismatch protection).
- src/lib/services/public-berths.ts: pure mapper with derivePublicStatus
  ("sold" wins; otherwise specific-interest junction OR
  status='under_offer' -> "Under Offer"; else "Available").
- 11 unit tests covering numeric coercion, status derivation,
  archived-berth handling, missing-map-data omission, and the
  status-precedence rule that "sold" trumps the specific-interest
  signal.

Smoke-tested: /api/public/berths -> 117 rows, A1 correctly shows
"Under Offer" (has interest_berths.is_specific_interest=true link),
INVALID -> 400, Z99 -> 404. Total tests: 996 -> 1007.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/app/api/public/health/route.ts

@@ -0,0 +1,25 @@
+import { NextResponse } from 'next/server';
+
+import { env } from '@/lib/env';
+
+/**
+ * GET /api/public/health
+ *
+ * Public-facing health probe. Used by the marketing-website server on
+ * startup to verify it's pointed at a CRM matching its own deployment
+ * env (plan §14.8 critical: prevent staging-website-talking-to-prod-CRM).
+ *
+ * Returns the CRM's `NODE_ENV` and `APP_URL` so the website can do a
+ * strict equality check before serving any request.
+ */
+export function GET(): Response {
+  return NextResponse.json(
+    {
+      status: 'ok',
+      env: env.NODE_ENV,
+      appUrl: env.APP_URL,
+      timestamp: new Date().toISOString(),
+    },
+    { headers: { 'cache-control': 'no-store' } },
+  );
+}