Convert src/ JavaScript modules to TypeScript

Renames every .js module under src/ to .ts (api, useResource,
adminSchema, navConfig, adminNav and src/data/*) and points imports,
comments and the seed script's module paths at the new names. Their
types now come from inference; no .d.ts files and no shape
interfaces.

tsc stays strict (noImplicitAny off). The errors inference leaves
behind get the lightest fix that clears them: `any` on empty state,
contexts and list defaults, `: any` on components with optional or
spread props, class fields on ApiError, and option shapes on
get/useResource.

Kept as real types, since they belong to modules that were already
TypeScript and later features import them: PageShell's ShellSection
and props, useContent's corrected record types (website/email/
instagram are bare strings) and EventListItem, and TimelineRef's
orgKind.

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

src/components/PageShell.tsx

@@ -29,9 +29,27 @@
      />
    ═══════════════════════════════════════════════════════════════ */
 
+import type { ReactNode } from "react";
+
 const TEAL = "#138ba0";
 
-export function Section({ section }) {
+export type ShellSection = {
+  id: string;
+  title: string;
+  blurb?: string;
+  accent: string;
+  background: string;
+  actions?: ReactNode;
+  content: ReactNode;
+};
+
+type PageShellProps = {
+  title: ReactNode;
+  intro?: ReactNode;
+  sections: ShellSection[];
+};
+
+export function Section({ section }: { section: ShellSection }) {
   const {
     id,
     title,
@@ -70,7 +88,7 @@ export function Section({ section }) {
   );
 }
 
-export default function PageShell({ title, intro, sections }) {
+export default function PageShell({ title, intro, sections }: PageShellProps) {
   return (
     <>
       {/* Page header */}