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>

components/marketing/legal-doc.tsx

@@ -1,23 +1,50 @@
+import { JsonLd } from "@/components/seo/json-ld";
+import { breadcrumbSchema, graph, webPageSchema } from "@/lib/schema";
+import { toIsoDate } from "@/lib/seo";
+
 export interface LegalSection {
   heading: string;
   paragraphs: string[];
   bullets?: string[];
 }
 
-/** Shared layout for long-form legal documents (Privacy, Terms). */
+/**
+ * Shared layout for long-form legal documents (Privacy, Terms, …).
+ *
+ * Also emits the page's structured data: every legal page has the same shape, so
+ * the WebPage + BreadcrumbList nodes are built here from `path`/`description`
+ * rather than repeated in each of the six route files.
+ */
 export function LegalDoc({
   title,
   updated,
   intro,
   sections,
+  path,
+  description,
 }: {
   title: string;
   updated: string;
   intro: string;
   sections: LegalSection[];
+  /** Root-relative URL of this document, e.g. "/terms". */
+  path: string;
+  /** Same one-line summary used for the page's meta description. */
+  description: string;
 }) {
+  const dateModified = toIsoDate(updated);
+
   return (
     <div className="container max-w-3xl py-20 md:py-24">
+      <JsonLd
+        data={graph(
+          {
+            ...webPageSchema({ path, name: title, description }),
+            ...(dateModified ? { dateModified } : {}),
+          },
+          breadcrumbSchema([{ name: title, path }])
+        )}
+      />
       <p className="text-[13px] font-semibold uppercase tracking-[0.04em] text-brand">Legal</p>
       <h1 className="mt-3 font-display text-4xl font-extrabold tracking-tight md:text-5xl">
         {title}