Connect rental-service with frontend via api gateway

This MR fixes several configuration issues that prevented the service from starting locally and aligns it with the multi-profile startup convention used across the platform.

Changes:

• application.yml — base config now only holds profile-agnostic settings (port, app name, multipart, autoconfigure exclusions). Datasource config removed from base to prevent accidental PostgreSQL connections when no profile is specified.
• application-dev.properties / application.properties — corrected server.port from 8080 to 3005 to match the port expected by the API Gateway route (rental-income-distributions-service-url).
• application-local.yml — updated datasource URL to localhost:5432 (standard local PostgreSQL), corrected database name to use underscores, and disabled Flyway to avoid schema management conflict with ddl-auto=update.
• docker-compose.yml — fixed port mapping from 5436:5437 (incorrect, PostgreSQL does not listen on 5437 inside the container) to 5438:5432 (host 5438 → container 5432, avoids conflict with existing local Postgres instances).
• pom.xml — changed H2 scope from test to runtime so the dev profile can boot with an in-memory database outside of the test lifecycle.