feat: make all service ports configurable via env variables

- Add API_PORT, INDEXER_PORT, MEILI_PORT, POSTGRES_PORT env variables
- Update docker-compose.yml to use ${VAR:-default} syntax for all ports
- Document new port variables in .env.example
- Allows users to customize ports to avoid conflicts with other services

.env.example

@@ -18,14 +18,22 @@ API_BOOTSTRAP_TOKEN=change-me-in-production
 # API Service
 API_LISTEN_ADDR=0.0.0.0:8080
 API_BASE_URL=http://api:8080
+API_PORT=8080
 
 # Indexer Service  
 INDEXER_LISTEN_ADDR=0.0.0.0:8081
 INDEXER_SCAN_INTERVAL_SECONDS=5
+INDEXER_PORT=8081
 
 # Backoffice Web UI
 BACKOFFICE_PORT=8082
 
+# Meilisearch Search Engine
+MEILI_PORT=7700
+
+# PostgreSQL Database
+POSTGRES_PORT=5432
+
 # =============================================================================
 # Database Configuration
 # =============================================================================