Fix the remaining type errors in src/

- Declare the --ig-fill custom property on React's CSSProperties once,
  instead of casting the style prop in Footer, Home and EventList-Cards.
- Type Footer's Get_In_Touch links as internal or external, so the
  external branch type-checks.
- Pass undefined rather than null for an absent gradient (Home) and
  Instagram URL (EventList-Cards).

tsc --noEmit is now clean, with and without --noImplicitAny.

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

src/components/Footer.tsx

@@ -39,7 +39,13 @@ const Social_Links = [
 // Only the label differs down here.
 const giveAction = NAV_ACTIONS.find((a) => a.variant === "fancy");
 
-const Get_In_Touch = [
+/* An internal route, or an off-site address opened in a new tab. */
+type TouchLink = { label: string } & (
+  | { external?: false; to: string }
+  | { external: true; href: string }
+);
+
+const Get_In_Touch: TouchLink[] = [
   { label: "Feedback",   to: "/feedback"},
   { label: "Contact Us", to: "/leadership#contact" },
 ];

src/pages/Home.tsx

@@ -300,7 +300,7 @@ export default function Home() {
                     className="rounded-3xl text-black overflow-hidden shadow-2xl h-full"
                     style={{
                       border: `1px solid ${color}`,
-                      background: ev.gradient,
+                      background: ev.gradient ?? undefined,
                       filter: past ? "saturate(0.75)" : "none",
                       pointerEvents: active ? "auto" : "none",
                     }}

src/pages/sections/EventList-Cards.tsx

@@ -199,7 +199,7 @@ export function Card({
   const igHandle = ev.instagram || null;
   const igUrl = igHandle
     ? `https://instagram.com/${igHandle.replace(/^@/, "")}`
-    : null;
+    : undefined;
 
   /* Off unless the caller says the band is mixed. A "Retreat" badge
      on every card in a row of nothing but retreats is noise, and

src/react-css.d.ts

@@ -0,0 +1,13 @@
+/* CSS custom properties set through a `style` prop. React's
+   CSSProperties only knows the standard ones, so each variable the
+   site sets inline is declared here once rather than cast at every
+   use. */
+
+import "react";
+
+declare module "react" {
+  interface CSSProperties {
+    /** The Instagram icon's hover fill; read by .ig-icon in index.css. */
+    "--ig-fill"?: string;
+  }
+}