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/build.gradle

@@ -0,0 +1,67 @@
+plugins {
+    id 'java'
+    id 'org.springframework.boot' version '3.3.5'
+    id 'io.spring.dependency-management' version '1.1.6'
+}
+
+group = 'com.tasteby'
+version = '0.1.0'
+
+java {
+    toolchain {
+        languageVersion = JavaLanguageVersion.of(21)
+    }
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    // Spring Boot
+    implementation 'org.springframework.boot:spring-boot-starter-web'
+    implementation 'org.springframework.boot:spring-boot-starter-jdbc'
+    implementation 'org.springframework.boot:spring-boot-starter-security'
+    implementation 'org.springframework.boot:spring-boot-starter-data-redis'
+    implementation 'org.springframework.boot:spring-boot-starter-validation'
+
+    // Oracle JDBC + Security (Wallet support for Oracle ADB)
+    implementation 'com.oracle.database.jdbc:ojdbc11:23.7.0.25.01'
+    implementation 'com.oracle.database.security:oraclepki:23.7.0.25.01'
+
+    // JWT
+    implementation 'io.jsonwebtoken:jjwt-api:0.12.6'
+    runtimeOnly 'io.jsonwebtoken:jjwt-impl:0.12.6'
+    runtimeOnly 'io.jsonwebtoken:jjwt-jackson:0.12.6'
+
+    // Google OAuth2 token verification
+    implementation 'com.google.api-client:google-api-client:2.7.0'
+
+    // OCI SDK (GenAI for LLM + Embeddings)
+    implementation 'com.oracle.oci.sdk:oci-java-sdk-generativeaiinference:3.49.0'
+    implementation 'com.oracle.oci.sdk:oci-java-sdk-common:3.49.0'
+
+    // Jackson for JSON
+    implementation 'com.fasterxml.jackson.core:jackson-databind'
+    implementation 'com.fasterxml.jackson.datatype:jackson-datatype-jsr310'
+
+    // YouTube Transcript API (Java port of youtube-transcript-api)
+    implementation 'io.github.thoroldvix:youtube-transcript-api:0.4.0'
+
+    // Playwright (browser-based transcript fallback)
+    implementation 'com.microsoft.playwright:playwright:1.49.0'
+
+    // HTTP client for YouTube/Google APIs
+    implementation 'org.springframework.boot:spring-boot-starter-webflux'
+
+    // Lombok
+    compileOnly 'org.projectlombok:lombok'
+    annotationProcessor 'org.projectlombok:lombok'
+
+    // Test
+    testImplementation 'org.springframework.boot:spring-boot-starter-test'
+}
+
+tasks.named('test') {
+    useJUnitPlatform()
+}