feat: age verification with an ID document (Didit), and closed registration (#4)

## Age verification with Didit

A new provider (`apps/api/src/age/didit.ts`) behind the existing vendor-neutral age interface. A person verifies once with an ID document, a passive liveness check and a face match; after that, all their linked IMVU accounts count as adult. The hub keeps only "over 18": never the document, photo or birth date.

- Webhooks are checked against Didit's signatures (the raw body or V2, with `-Previous` during secret rotation), and old ones are rejected. If the webhook has no decision, the hub fetches it from Didit.
- A later answer replaces an earlier one. An approval that's taken back (say, after a manual review) becomes `revoked`. A check still in review stays pending.
- Limits, for every provider: one unfinished check per person (starting again resumes it), at most 3 checks in 30 days, none once verified, and a monthly cap (`DIDIT_MONTHLY_LIMIT`, default 30: since 2026-11-01, Didit's free plan is $10 of credit a month, and a check costs $0.30).
- People are only ever sent back to the hub's website.
- The Account page gets an Age Verification card.
- Configuration: `AGE_PROVIDERS=imvu,didit`, `DIDIT_API_KEY`, `DIDIT_WORKFLOW_ID`, `DIDIT_WEBHOOK_SECRET`. The webhook is `<API_URL>/api/v1/age/webhook/didit`.

## Closed registration

Registration is open or closed. It's an admin's setting in the console, with its default from `REGISTRATION`.

- When it's closed, new accounts can only sign in until a moderator approves them, or declines them (which deletes the account).
- The website shows people who are waiting a waiting page, and the API treats them as signed out everywhere but `/me`.
- The console gets a Waiting count, a Waiting for approval filter, Approve and Decline on a person's page, and a Registration setting.
- The migration adds `user.approved` (existing accounts stay approved) and `hub_setting`.

## Testing

- New tests cover Didit (with a fake Didit server), the limits, revocation, return addresses and registration.
- `bun run test`: 35 pass. `bun run check-types` passes.
- Checked locally: the account, waiting, sign-up and console pages render.
- Not run against Didit itself yet. The sandbox workflow "T5DE Age Check" is published, and the next step is a real webhook once this is on staging.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

## Age verification with Didit

A new provider (`apps/api/src/age/didit.ts`) behind the existing vendor-neutral age interface. A person verifies once with an ID document, a passive liveness check and a face match; after that, all their linked IMVU accounts count as adult. The hub keeps only "over 18": never the document, photo or birth date.

- Webhooks are checked against Didit's signatures (the raw body or V2, with `-Previous` during secret rotation), and old ones are rejected. If the webhook has no decision, the hub fetches it from Didit.
- A later answer replaces an earlier one. An approval that's taken back (say, after a manual review) becomes `revoked`. A check still in review stays pending.
- Limits, for every provider: one unfinished check per person (starting again resumes it), at most 3 checks in 30 days, none once verified, and a monthly cap (`DIDIT_MONTHLY_LIMIT`, default 30: since 2026-11-01, Didit's free plan is $10 of credit a month, and a check costs $0.30).
- People are only ever sent back to the hub's website.
- The Account page gets an Age Verification card.
- Configuration: `AGE_PROVIDERS=imvu,didit`, `DIDIT_API_KEY`, `DIDIT_WORKFLOW_ID`, `DIDIT_WEBHOOK_SECRET`. The webhook is `<API_URL>/api/v1/age/webhook/didit`.

## Closed registration

Registration is open or closed. It's an admin's setting in the console, with its default from `REGISTRATION`.

- When it's closed, new accounts can only sign in until a moderator approves them, or declines them (which deletes the account).
- The website shows people who are waiting a waiting page, and the API treats them as signed out everywhere but `/me`.
- The console gets a Waiting count, a Waiting for approval filter, Approve and Decline on a person's page, and a Registration setting.
- The migration adds `user.approved` (existing accounts stay approved) and `hub_setting`.

## Testing

- New tests cover Didit (with a fake Didit server), the limits, revocation, return addresses and registration.
- `bun run test`: 35 pass. `bun run check-types` passes.
- Checked locally: the account, waiting, sign-up and console pages render.
- Not run against Didit itself yet. The sandbox workflow "T5DE Age Check" is published, and the next step is a real webhook once this is on staging.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: dhkatz <[email protected]>

apps/web/app/signup/page.tsx

@@ -1,15 +1,20 @@
 import type { Metadata } from "next";
 import { redirect } from "next/navigation";
 import { NarrowCard } from "@/components/narrow-card";
-import { getMe } from "@/lib/api";
+import { api, getMe, unwrap } from "@/lib/api";
 import { SignUpForm } from "./signup-form";
 
 export const metadata: Metadata = { title: "Create account" };
 
 export default async function SignUp() {
   if (await getMe()) redirect("/account");
+  const { registration } = unwrap(await api.hub.get());
+  const description =
+    registration === "closed"
+      ? "One T5DE account for all your IMVU accounts. New accounts need a moderator's approval."
+      : "One T5DE account for all your IMVU accounts.";
   return (
-    <NarrowCard title="Create account" description="One T5DE account for all your IMVU accounts.">
+    <NarrowCard title="Create account" description={description}>
       <SignUpForm />
     </NarrowCard>
   );