feat: add github oauth configuration

apps/blog/auth.config.ts

@@ -0,0 +1,19 @@
+import GitHub from '@auth/core/providers/github';
+import { defineConfig } from 'auth-astro';
+
+export default defineConfig({
+  providers: [
+    GitHub({
+      clientId: import.meta.env.GITHUB_CLIENT_ID,
+      clientSecret: import.meta.env.GITHUB_CLIENT_SECRET,
+    }),
+  ],
+  callbacks: {
+    session({ session, token }) {
+      if (session.user && token.sub) {
+        session.user.id = token.sub;
+      }
+      return session;
+    },
+  },
+});