Feat: 기본 환경 변수 및 설정 추가

# Conflicts:
#	build.gradle.kts
#	src/main/resources/application.yml

Author: joyewon0705

.env.default

@@ -0,0 +1 @@
+JWT_SECRET=your-secret-key

build.gradle.kts

@@ -39,6 +39,11 @@ dependencies {
     testRuntimeOnly("org.junit.platform:junit-platform-launcher")
     implementation("org.springdoc:springdoc-openapi-starter-webmvc-ui:2.8.13")
     implementation ("io.github.cdimascio:dotenv-java:3.0.0")
+
+    // 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")
 }
 
 tasks.withType<Test> {