feat: add Spring Boot application entry point and base configuration

- Create SkillhubApplication main class
- Add application.yml with JPA, Flyway, graceful shutdown config
- Add application-local.yml for local development profile
- Add database and Redis dependencies to skillhub-app POM

server/skillhub-app/pom.xml

@@ -39,6 +39,32 @@
             <groupId>com.skillhub</groupId>
             <artifactId>skillhub-infra</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-jpa</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.postgresql</groupId>
+            <artifactId>postgresql</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.flywaydb</groupId>
+            <artifactId>flyway-core</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.flywaydb</groupId>
+            <artifactId>flyway-database-postgresql</artifactId>
+            <version>10.10.0</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-redis</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.session</groupId>
+            <artifactId>spring-session-data-redis</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-test</artifactId>

server/skillhub-app/src/main/java/com/skillhub/SkillhubApplication.java

@@ -0,0 +1,11 @@
+package com.skillhub;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class SkillhubApplication {
+    public static void main(String[] args) {
+        SpringApplication.run(SkillhubApplication.class, args);
+    }
+}

server/skillhub-app/src/main/resources/application-local.yml

@@ -0,0 +1,20 @@
+spring:
+  jpa:
+    hibernate:
+      ddl-auto: validate
+    show-sql: true
+  flyway:
+    enabled: true
+  datasource:
+    url: jdbc:postgresql://localhost:5432/skillhub
+    username: skillhub
+    password: skillhub_dev
+  data:
+    redis:
+      host: localhost
+      port: 6379
+
+logging:
+  level:
+    com.skillhub: DEBUG
+    org.springframework.security: DEBUG

server/skillhub-app/src/main/resources/application.yml

@@ -0,0 +1,34 @@
+server:
+  port: 8080
+  shutdown: graceful
+
+spring:
+  application:
+    name: skillhub
+  lifecycle:
+    timeout-per-shutdown-phase: 30s
+  jpa:
+    hibernate:
+      ddl-auto: validate
+    open-in-view: false
+    properties:
+      hibernate:
+        dialect: org.hibernate.dialect.PostgreSQLDialect
+  flyway:
+    enabled: true
+    locations: classpath:db/migration
+  datasource:
+    url: jdbc:postgresql://localhost:5432/skillhub
+    username: skillhub
+    password: skillhub_dev
+    hikari:
+      maximum-pool-size: 10
+
+management:
+  endpoints:
+    web:
+      exposure:
+        include: health,info
+  endpoint:
+    health:
+      show-details: when-authorized