revert(ai): Revert initialize-schema to false

Reverting to original configuration. Will manually create
spring_ai_chat_memory table instead to avoid potential CLOB errors.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: JIWONKIMS

src/main/resources/application-prod.yml

@@ -23,7 +23,7 @@ spring:
   ai:
     vectorstore:
       jdbc:
-        initialize-schema: true
+        initialize-schema: false
 
   data:
     redis:  # 캐싱 전용 (세션 저장 안함 - JWT 기반 stateless 인증 사용)