chore: env doğrulama, Vitest, Prettier ve editör ayarları

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

.gitignore

@@ -30,8 +30,9 @@ yarn-debug.log*
 yarn-error.log*
 .pnpm-debug.log*
 
-# env files (can opt-in for committing if needed)
+# env files (only the example is committed)
 .env*
+!.env.example
 
 # vercel
 .vercel
@@ -39,3 +40,9 @@ yarn-error.log*
 # typescript
 *.tsbuildinfo
 next-env.d.ts
+
+# user uploads (never committed; backed up separately)
+/uploads/
+
+# local tooling
+/scratch/