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/account/actions.ts

@@ -1,5 +1,6 @@
 "use server";
 import { revalidatePath } from "next/cache";
+import { redirect } from "next/navigation";
 import { api, unwrap } from "@/lib/api";
 import { attempt, field, type ActionState } from "@/lib/actions";
 
@@ -58,3 +59,15 @@ export async function signOutComputers(_: ActionState, _form: FormData): Promise
     return "Signed out everywhere.";
   });
 }
+
+/** Starts an age check with a provider that checks the person, and sends them to its page. */
+export async function startAgeCheck(_: ActionState, form: FormData): Promise<ActionState> {
+  let url: string | undefined;
+  const state = await attempt(async () => {
+    const started = unwrap(await api.age({ provider: field(form, "provider") }).start.post({ returnURL: "/account?age=back" }));
+    if (started.kind === "redirect") url = started.url;
+    done();
+  });
+  if (url) redirect(url);
+  return state;
+}