feat: initialize Gradle multi-module backend and Vite frontend

backend/im-service/build.gradle.kts

@@ -0,0 +1,40 @@
+plugins {
+    kotlin("jvm") version "2.4.10"
+    kotlin("plugin.spring") version "2.4.10"
+    id("org.springframework.boot") version "4.1.0"
+    id("io.spring.dependency-management") version "1.1.7"
+}
+
+group = "com.msksbr.imSystem"
+version = "0.1.0-SNAPSHOT"
+
+java {
+    toolchain {
+        languageVersion = JavaLanguageVersion.of(21)
+    }
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation("org.springframework.boot:spring-boot-starter-web")
+    implementation("org.springframework.boot:spring-boot-starter-kafka")
+
+    implementation("com.fasterxml.jackson.module:jackson-module-kotlin")
+    implementation("org.jetbrains.kotlin:kotlin-reflect")
+
+    testImplementation("org.springframework.boot:spring-boot-starter-test")
+    testRuntimeOnly("org.junit.platform:junit-platform-launcher")
+}
+
+kotlin {
+    compilerOptions {
+        freeCompilerArgs.addAll("-Xjsr305=strict", "-Xannotation-default-target=param-property")
+    }
+}
+
+tasks.withType<Test> {
+    useJUnitPlatform()
+}

backend/im-service/src/main/kotlin/com/im/imservice/ImServiceApplication.kt

@@ -0,0 +1,11 @@
+package com.im.imservice
+
+import org.springframework.boot.autoconfigure.SpringBootApplication
+import org.springframework.boot.runApplication
+
+@SpringBootApplication
+class ImServiceApplication
+
+fun main(args: Array<String>) {
+    runApplication<ImServiceApplication>(*args)
+}

backend/im-service/src/main/resources/application.yml

@@ -0,0 +1,16 @@
+server:
+  port: 8081
+
+spring:
+  application:
+    name: im-service
+
+  kafka:
+    bootstrap-servers: ${KAFKA_BOOTSTRAP_SERVERS:localhost:9092}
+    producer:
+      key-serializer: org.apache.kafka.common.serialization.StringSerializer
+      value-serializer: org.apache.kafka.common.serialization.StringSerializer
+
+im:
+  kafka:
+    log-topic: im-logs