feat: scaffold Astro 7 with Tailwind 4, MDX, sitemap, node adapter and tooling

- Tailwind v4 via @tailwindcss/vite + typography plugin
- astro-icon (Tabler), self-hosted Rubik/Inter, RSS, Pagefind postbuild
- Prettier (astro + tailwind plugins), editorconfig
- new:post script with Turkish-aware slugify

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

src/lib/slug.ts

@@ -0,0 +1,25 @@
+const TR_MAP: Record<string, string> = {
+  ç: 'c',
+  ğ: 'g',
+  ı: 'i',
+  İ: 'i',
+  ö: 'o',
+  ş: 's',
+  ü: 'u',
+  Ç: 'c',
+  Ğ: 'g',
+  Ö: 'o',
+  Ş: 's',
+  Ü: 'u',
+};
+
+/** Turkish-aware slugify: "Çift Bant Anten" → "cift-bant-anten". */
+export function slugify(input: string): string {
+  return input
+    .replace(/[çğıİöşüÇĞÖŞÜ]/g, (ch) => TR_MAP[ch] ?? ch)
+    .normalize('NFKD')
+    .replace(/[̀-ͯ]/g, '')
+    .toLowerCase()
+    .replace(/[^a-z0-9]+/g, '-')
+    .replace(/^-+|-+$/g, '');
+}