feat(epic1): complete OpenTelemetry integration and add verification documentation

Story 1.6: OpenTelemetry Distributed Tracing
- Implemented tracer initialization with stdout (dev) and OTLP (prod) exporters
- Added HTTP request instrumentation via Gin middleware
- Integrated trace ID correlation in structured logs
- Added tracing configuration to config files
- Registered tracer provider in DI container

Documentation and Setup:
- Created Docker Compose setup for PostgreSQL database
- Added comprehensive Epic 1 summary with verification instructions
- Added Epic 0 summary with verification instructions
- Linked summaries in documentation index and epic READMEs
- Included detailed database testing instructions
- Added Docker Compose commands and troubleshooting guide

All Epic 1 stories (1.1-1.6) are now complete. Story 1.7 depends on Epic 2.

docker-compose.yml

@@ -0,0 +1,30 @@
+version: '3.8'
+
+services:
+  postgres:
+    image: postgres:16-alpine
+    container_name: goplt-postgres
+    environment:
+      POSTGRES_USER: goplt
+      POSTGRES_PASSWORD: goplt_password
+      POSTGRES_DB: goplt
+    ports:
+      - "5432:5432"
+    volumes:
+      - postgres_data:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U goplt"]
+      interval: 5s
+      timeout: 5s
+      retries: 5
+    networks:
+      - goplt-network
+
+volumes:
+  postgres_data:
+    driver: local
+
+networks:
+  goplt-network:
+    driver: bridge
+