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/EventDetail.tsx

@@ -18,7 +18,7 @@
 
 import { Link, useParams } from 'react-router-dom'
 
-import PageShell from '../components/PageShell.tsx'
+import PageShell, { type ShellSection } from '../components/PageShell.tsx'
 import PageState from '../components/PageState.tsx'
 import ContentBlocks from '../components/ContentBlocks.tsx'
 import PeopleTiles, { type PeopleGroupInput } from '../components/PeopleTiles.tsx'
@@ -85,7 +85,7 @@ export default function EventDetail() {
   const accent = event.color || TEAL
   const groups = peopleGroups(event.people, accent)
 
-  const sections = [
+  const sections: ShellSection[] = [
     {
       id: 'about',
       title: event.theme || 'About',