Initial implementation for the backend persistence of activities (#5)

Reviewed-on: #5
Co-authored-by: Jarno Kiesiläinen <jarnokie@gmail.com>
Co-committed-by: Jarno Kiesiläinen <jarnokie@gmail.com>

backend/src/main/resources/application.yml

@@ -9,27 +9,21 @@ spring:
   
   # Database Configuration
   datasource:
-    url: jdbc:h2:mem:testdb
-    driver-class-name: org.h2.Driver
-    username: sa
-    password: password
+    url: jdbc:postgresql://localhost:5432/vibing
+    username: vibing
+    password: vibing
+    driver-class-name: org.postgresql.Driver
   
   # JPA Configuration
   jpa:
-    database-platform: org.hibernate.dialect.H2Dialect
+    database-platform: org.hibernate.dialect.PostgreSQLDialect
     hibernate:
-      ddl-auto: create-drop
+      ddl-auto: update
     show-sql: true
     properties:
       hibernate:
         format_sql: true
   
-  # H2 Console (for development)
-  h2:
-    console:
-      enabled: true
-      path: /h2-console
-  
   # Jackson Configuration
   jackson:
     default-property-inclusion: non_null