Migrate backend from Python to Java Spring Boot

- Full Java 21 + Spring Boot 3.3 backend with Virtual Threads
- HikariCP connection pool for Oracle ADB
- JWT auth, Redis caching, OCI GenAI integration
- YouTube transcript extraction via API + Playwright browser fallback
- SSE streaming for bulk operations
- Scheduled daemon for channel scanning/video processing
- Mobile UI: collapse restaurant list to single row on selection
- Switch PM2 ecosystem config to Java backend

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

backend-java/src/main/java/com/tasteby/config/RedisConfig.java

@@ -0,0 +1,15 @@
+package com.tasteby.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.redis.connection.RedisConnectionFactory;
+import org.springframework.data.redis.core.StringRedisTemplate;
+
+@Configuration
+public class RedisConfig {
+
+    @Bean
+    public StringRedisTemplate stringRedisTemplate(RedisConnectionFactory connectionFactory) {
+        return new StringRedisTemplate(connectionFactory);
+    }
+}