feat: SEO altyapısı — pre-render, meta tags, blog posts, robots/sitemap

- vite-plugin-prerender yerine Playwright tabanlı post-build pre-render scripti
  (apps/web/scripts/prerender.mjs): 10 public route statik HTML'e dönüştürülüyor
- usePageMeta hook: her public route'da özgün title/description/canonical/OG tags
- index.html: favicon.svg, canonical, OG/Twitter Card, geliştirilmiş title+desc
- apps/web/public/: robots.txt, sitemap.xml (10 URL), favicon.svg
- nginx HSTS header eklendi (Strict-Transport-Security)
- Blog post sayfaları: blog_/$slug.tsx (4 tam yazı, 600-800 kelime)
- blog.tsx: post kartlarına Link eklendi
- Homepage: Schema.org JSON-LD (Organization + SoftwareApplication)
- Footer: placeholder href="#" sosyal linkler kaldırıldı
- deploy.sh + deploy.yml: playwright install chromium + prerender adımı

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/api/src/auth/auth.ts

@@ -3,9 +3,9 @@ import { drizzleAdapter } from "better-auth/adapters/drizzle";
 import { drizzle } from "drizzle-orm/postgres-js";
 import postgres from "postgres";
 import { randomUUID } from "crypto";
-
 import * as schema from "../database/schema/core";
 import type { EmailService } from "../email/email.service";
+import { generateReferralCode } from "@sase/shared";
 
 let authInstance: ReturnType<typeof betterAuth> | null = null;
 
@@ -69,6 +69,20 @@ export function createAuth(databaseUrl: string, secret: string, baseUrl: string,
           },
         }
       : {}),
+    databaseHooks: {
+      user: {
+        create: {
+          before: async (userData) => {
+            return {
+              data: {
+                ...userData,
+                referralCode: generateReferralCode(),
+              },
+            };
+          },
+        },
+      },
+    },
     session: {
       cookieCache: {
         enabled: true,