feat(eslint): add eslint flat config

.eslint/shared.ts

@@ -0,0 +1,41 @@
+export const sharedFiles = [
+  "**/*.js",
+  "**/*.cjs",
+  "**/*.mjs",
+  "**/*.jsx",
+  "**/*.ts",
+  "**/*.cts",
+  "**/*.mts",
+  "**/*.tsx",
+  "**/*.d.ts",
+];
+
+export const sharedTestFiles = [
+  "**/*.test.{ts,tsx,js,jsx}",
+  "**/*.spec.{ts,tsx,js,jsx}",
+  "**/tests/**/*.{ts,tsx,js,jsx}",
+  "**/__tests__/**/*.{ts,tsx,js,jsx}",
+];
+
+export const astroFiles = ["**/*.astro"];
+
+export const typescriptFiles = [
+  "**/*.ts",
+  "**/*.tsx",
+  "**/*.mts",
+  "**/*.cts",
+  "**/*.d.ts",
+];
+
+export const javascriptFiles = ["**/*.js", "**/*.jsx", "**/*.mjs", "**/*.cjs"];
+
+export const configFiles = [
+  "*.config.{ts,js,mjs}",
+  "**/*.config.{ts,js,mjs}",
+  "**/vite.config.*",
+  "**/vitest.config.*",
+  "**/playwright.config.*",
+  "**/astro.config.*",
+  "**/tailwind.config.*",
+  "**/eslint.config.*",
+];