Type src/ against API and database shapes, fixing implicit anys

Adds .d.ts declarations beside the untyped JS modules imported from
TS (api.js, navConfig.js, adminSchema.js, adminNav.js, src/data/*),
with shapes taken from the server routes and migrations. get/post/
patch/del now return unknown unless the caller names the response.

Fixes found along the way:
- website/email/instagram are bare strings from splitLinks, not Link
  objects; OrganizationDetail's website and email pills rendered with
  no href or label and now link correctly.
- The chapter map falls back to FALLBACK_COLOR for a region with no
  colour instead of painting its tiles black.

Adds defineSection() so each page manifest entry's props are checked
against its own Component.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/pages/admin/AdminLogin.tsx

@@ -10,7 +10,7 @@
    starts working.
    ═══════════════════════════════════════════════════════════════ */
 
-import { useState } from "react";
+import { useState, type FormEvent } from "react";
 import { useLocation, useNavigate } from "react-router-dom";
 
 import { useAuth } from "../../lib/auth.tsx";
@@ -29,12 +29,12 @@ export default function AdminLogin() {
 
   const [email, setEmail] = useState("");
   const [password, setPassword] = useState("");
-  const [error, setError] = useState(null);
+  const [error, setError] = useState<string | null>(null);
   const [busy, setBusy] = useState(false);
 
   const destination = location.state?.from?.pathname ?? "/admin/home";
 
-  async function handleSubmit(event) {
+  async function handleSubmit(event: FormEvent<HTMLFormElement>) {
     event.preventDefault();
     if (busy) return;