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/app/layout.tsx

@@ -54,6 +54,11 @@ export const metadata: Metadata = {
     title: "famapp",
   },
   icons: {
+    icon: [
+      { url: "/favicon.svg", type: "image/svg+xml" },
+      { url: "/icon-32.png", sizes: "32x32", type: "image/png" },
+      { url: "/icon-16.png", sizes: "16x16", type: "image/png" },
+    ],
     apple: "/icon-180.png",
   },
 };