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>

worker/index.ts

@@ -8,7 +8,7 @@ import {
   type EchoPayload,
 } from "@/lib/queue/jobs";
 import { runEpisodeGeneration, refundEpisodeUsage } from "@/lib/ai/pipeline/generate-episode";
-import { setEpisodeStatus } from "@/lib/episodes/status";
+import { failEpisode } from "@/lib/episodes/status";
 import { recordHeartbeat } from "@/lib/queue/health";
 
 const HEARTBEAT_NAME = "generation-worker";
@@ -89,7 +89,8 @@ async function handleGenerate(job: {
       } catch (refundErr) {
         console.error(`[generate] ${episodeId} usage refund failed`, refundErr);
       }
-      await setEpisodeStatus(episodeId, "FAILED", { errorMessage: message });
+      // Raw `message` goes to the job row (admin-only); the user sees generic copy.
+      await failEpisode(episodeId, message);
     } else {
       throw err; // let pg-boss retry with backoff
     }