Remove environment variable defaults and align with docker-compose

- Remove default values from database environment variables
- Use POSTGRES_USERNAME/PASSWORD to match docker-compose.yaml
- Use DB_URL without default to ensure explicit configuration

src/main/resources/application-prod.properties

@@ -1,9 +1,9 @@
 api.baseUrl=https://cftunnels.hithomelabs.com
 
 # Production Database Configuration
-spring.datasource.url=${PROD_DB_URL:jdbc:postgresql://postgres:5432/cftunnel}
-spring.datasource.username=${PROD_DB_USERNAME:postgres}
-spring.datasource.password=${PROD_DB_PASSWORD}
+spring.datasource.url=${DB_URL}
+spring.datasource.username=${POSTGRES_USERNAME}
+spring.datasource.password=${POSTGRES_PASSWORD}
 spring.datasource.driver-class-name=org.postgresql.Driver
 
 # JPA Configuration

src/main/resources/application-test.properties

@@ -1,9 +1,9 @@
 api.baseUrl=https://testcf.hithomelabs.com
 
 # Test Database Configuration - Same as Production
-spring.datasource.url=${TEST_DB_URL:jdbc:postgresql://postgres:5432/cftunnel}
-spring.datasource.username=${TEST_DB_USERNAME:postgres}
-spring.datasource.password=${TEST_DB_PASSWORD}
+spring.datasource.url=${DB_URL}
+spring.datasource.username=${POSTGRES_USERNAME}
+spring.datasource.password=${POSTGRES_PASSWORD}
 spring.datasource.driver-class-name=org.postgresql.Driver
 
 # JPA Configuration