feat: proper logo, favicon, and pwa icons

- replace placeholder house svg with clean geometric house mark
  on indigo-700 (#4338CA) — roof triangle, body, door cutout
- add favicon.svg with prefers-color-scheme dark variant
- add icon-16/32 sizes; regenerate all pngs from svg via sharp
- update BrandMark component to use inline svg house instead of 'f'
- wire favicon + sized pngs into layout metadata
- fix middleware to allow icon/manifest/favicon paths without auth
  (android launcher fetches icons in a cookieless system context)
- fix getCurrentSession() to redirect to /login instead of throwing
  when session cookie is stale/invalid

src/lib/session.ts

@@ -1,4 +1,5 @@
 import { eq } from "drizzle-orm";
+import { redirect } from "next/navigation";
 import { auth } from "@/lib/auth";
 import { db } from "@/lib/db";
 import { householdMembers, households, users } from "@/modules/_core/schema";
@@ -13,7 +14,7 @@ export interface CurrentSession {
 
 export async function getCurrentSession(): Promise<CurrentSession> {
   const session = await auth();
-  if (!session?.user?.id) throw new Error("Not authenticated");
+  if (!session?.user?.id) redirect("/login");
 
   const [row] = await db
     .select({