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/components/PeopleTiles.tsx

@@ -164,7 +164,7 @@ export default function PeopleTiles({
 
     Promise.all(
       specs.map((spec) =>
-        get(`/teams/${spec.id}/people`, { ttl }).then((data: TeamResponse) => ({
+        get<TeamResponse>(`/teams/${spec.id}/people`, { ttl }).then((data) => ({
           spec,
           data,
         })),
@@ -198,8 +198,8 @@ export default function PeopleTiles({
     let live = true;
     setFailed(false);
 
-    get(`/people?ids=${encodeURIComponent(slugKey)}`, { ttl })
-      .then((data: { people: Person[] }) => {
+    get<{ people: Person[] }>(`/people?ids=${encodeURIComponent(slugKey)}`, { ttl })
+      .then((data) => {
         if (!live) return;
         const byId: Record<string, Person> = {};
         for (const person of data.people) byId[String(person.id)] = person;
@@ -304,11 +304,10 @@ function resolveAll(
     }
 
     const { peopleslug, ...overrides } = entry;
-    const merged: Person = { ...base };
-    for (const [key, value] of Object.entries(overrides)) {
-      if (value !== undefined) (merged as Record<string, unknown>)[key] = value;
-    }
-    resolved.push(merged);
+    const defined: Partial<Person> = Object.fromEntries(
+      Object.entries(overrides).filter(([, value]) => value !== undefined),
+    );
+    resolved.push({ ...base, ...defined });
   }
 
   return resolved;