Initial project setup: CI, Docker & configs

Add project bootstrap for build, CI/CD, and local development. Introduces Maven Wrapper (mvnw, mvnw.cmd, .mvn/wrapper), multi-stage Dockerfile, docker-compose files (compose.yaml, docker-compose.dev.yml), .env, banner and README. Adds Gitea Actions workflow to build, test and push container images. Update application.yml (port -> 8090, virtual threads, API versioning, management/actuator/prometheus settings, Steam API config) and add application-dev.yml for local overrides. Extend pom.xml with caching, observability (actuator, micrometer/prometheus), testing/dev dependencies (testcontainers, devtools, additional spring test modules) to support CI and local testing.

compose.yaml

@@ -0,0 +1,10 @@
+services:
+  postgres:
+    image: postgres:17-alpine
+    container_name: tbp_core_db_local
+    ports:
+      - "5433:5432"
+    environment:
+      - POSTGRES_DB=tbp_core
+      - POSTGRES_USER=tbp_user
+      - POSTGRES_PASSWORD=local_secret_password