fix: Allow /actuator/health endpoint for health checks

Added /actuator/health to permitAll in SecurityConfig to enable
container health checks during Blue/Green deployment.

Without this, health checks fail due to authentication requirement,
causing deployment rollback.

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

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

Author: JIWONKIMS

src/main/kotlin/com/back/koreaTravelGuide/common/security/SecurityConfig.kt

@@ -60,6 +60,7 @@ class SecurityConfig(
                 authorize("/h2-console/**", permitAll)
                 authorize("/swagger-ui/**", "/v3/api-docs/**", permitAll)
                 authorize("/api/auth/**", permitAll)
+                authorize("/actuator/health", permitAll)
                 authorize("/favicon.ico", permitAll)
                 if (isDev) {
                     authorize(anyRequest, permitAll)