feat: Cloudflare Turnstile on auth, CSP fixes, admin/SEO/analytics additions

Turnstile bot protection (sign-in, sign-up, password-reset):
- Register Better Auth's captcha plugin with the cloudflare-turnstile
  provider; endpoints listed explicitly rather than relying on defaults.
  /reset-password is intentionally excluded — it is reached only via a
  single-use emailed token.
- Add an explicit-render Turnstile widget component. Tokens are single-use,
  so each form resets the challenge after a failed submit; submit stays
  disabled until a token is held.
- Read the site key server-side and pass it down as a prop, so rotating it
  does not require a rebuild.
- Fail fast in production when TURNSTILE_SECRET_KEY is missing, and when a
  secret is set without a site key (that combination would demand a token
  no form can produce, locking every user out).
- Pass a throwaway secret during `next build` in the Dockerfile, mirroring
  the existing BETTER_AUTH_SECRET treatment, so image builds don't need it.

CSP fixes in middleware (these blocked Turnstile entirely):
- Add frame-src for challenges.cloudflare.com. Without it the widget's
  iframe fell back to default-src 'self' and was blocked outright.
- Allow 'unsafe-eval' and websockets in DEVELOPMENT only. `next dev`
  compiles with eval(), so the strict policy threw EvalError and killed
  hydration — no client JS ran at all, which also meant form submit
  handlers never fired. Production policy is unchanged and still strict.

Also included (concurrent work in the tree):
- Admin organizations pages and lib/admin/orgs.
- Episode moderation migration, SEO metadata (sitemap, robots, JSON-LD,
  OG/Twitter images, manifest), Umami analytics, not-found page.

Local dev database: docker-compose.dev.yml provisions Postgres 18 on port
5443 (5432-5442 are in use by other local projects).

Note: `npx tsc --noEmit` currently fails in app/(app)/team/page.tsx — an
`invitations` prop the component does not accept. This predates the commit
and will fail `next build` until fixed.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

app/api/v1/episodes/route.ts

@@ -2,7 +2,7 @@ import { NextRequest } from "next/server";
 import { z } from "zod";
 import { verifyApiKey, bearerKey } from "@/lib/apikeys";
 import { prisma } from "@/lib/db";
-import { getEffectivePlan } from "@/lib/billing/subscription";
+import { getEffectivePlan, subjectHasFeature } from "@/lib/billing/subscription";
 import { reserveLimit, LimitExceededError } from "@/lib/usage/limits";
 import { refundUsage } from "@/lib/usage/meter";
 import { enqueueEpisodeGeneration } from "@/lib/queue/pgboss";
@@ -19,11 +19,30 @@ async function authorize(req: NextRequest) {
   return verifyApiKey(bearerKey(req.headers.get("authorization")));
 }
 
+/**
+ * Re-check the `api_access` entitlement on every request.
+ *
+ * Key CREATION gates on this feature, but a key outlives the subscription that
+ * minted it: without this check a user could subscribe, mint a key, downgrade to
+ * Free, and keep programmatic access to a paid feature indefinitely.
+ * Returns a 402 Response when the entitlement is gone, else null.
+ */
+async function requireApiAccess(userId: string): Promise<Response | null> {
+  if (await subjectHasFeature(userId, "api_access")) return null;
+  return Response.json(
+    { error: "API access requires an active Pro or Agency plan." },
+    { status: 402 }
+  );
+}
+
 /** GET /api/v1/episodes — list the caller's episodes. */
 export async function GET(req: NextRequest) {
   const auth = await authorize(req);
   if (!auth) return Response.json({ error: "Invalid API key" }, { status: 401 });
 
+  const denied = await requireApiAccess(auth.userId);
+  if (denied) return denied;
+
   const rl = await rateLimit("read", auth.userId, LIMITS.read);
   if (!rl.ok) {
     return Response.json(
@@ -56,6 +75,9 @@ export async function POST(req: NextRequest) {
   const auth = await authorize(req);
   if (!auth) return Response.json({ error: "Invalid API key" }, { status: 401 });
 
+  const denied = await requireApiAccess(auth.userId);
+  if (denied) return denied;
+
   const rl = await rateLimit("api", auth.userId, LIMITS.api);
   if (!rl.ok) {
     return Response.json(