feat: visual polish & UX — fade-in, theme toggle, scroll-to-top, footer, cursor, badge

- Add FadeIn component (IntersectionObserver scroll-reveal + load animation)
- Add dark/light theme toggle (useSyncExternalStore + localStorage)
- Add scroll-to-top button (appears after 300px scroll)
- Add configurable footer with social links (gallery.yaml)
- Add crosshair cursor on photo grid items
- Add 'X photos' count badge on subpage cover images
- Add light theme color palette in tokens.css

eslint.config.mjs

@@ -1,17 +1,38 @@
-import { defineConfig, globalIgnores } from "eslint/config";
-import nextVitals from "eslint-config-next/core-web-vitals";
-import nextTs from "eslint-config-next/typescript";
+import { defineConfig, globalIgnores } from 'eslint/config';
+import nextVitals from 'eslint-config-next/core-web-vitals';
+import nextTs from 'eslint-config-next/typescript';
+import prettier from 'eslint-config-prettier';
+import prettierPlugin from 'eslint-plugin-prettier';
 
 const eslintConfig = defineConfig([
   ...nextVitals,
   ...nextTs,
+  {
+    plugins: {
+      prettier: prettierPlugin,
+    },
+    rules: {
+      'prettier/prettier': 'error',
+      'no-console': 'warn',
+      '@typescript-eslint/no-unused-vars': [
+        'error',
+        {
+          argsIgnorePattern: '^_',
+          varsIgnorePattern: '^_',
+          caughtErrorsIgnorePattern: '^_',
+        },
+      ],
+      '@typescript-eslint/no-explicit-any': 'warn',
+    },
+  },
+  prettier,
   // Override default ignores of eslint-config-next.
   globalIgnores([
     // Default ignores of eslint-config-next:
-    ".next/**",
-    "out/**",
-    "build/**",
-    "next-env.d.ts",
+    '.next/**',
+    'out/**',
+    'build/**',
+    'next-env.d.ts',
   ]),
 ]);