feat(lab-04): complete Phase 5 - Storage & S3 lab

Phase Plan:
- 05-PLAN.md: Combined execution plan for efficiency
- 05-RESEARCH.md: Domain research on volumes and MinIO

Test Scripts (4):
- 01-volumes-test.sh: Volume persistence verification
- 02-minio-test.sh: MinIO S3 API testing
- 03-persistence-test.sh: Database persistence verification
- 99-final-verification.sh: End-to-end verification

Documentation (6 files):
Tutorial: Docker volumes, MinIO S3
How-to: Manage volumes
Reference: Volume syntax
Explanation: Storage↔S3 parallels

Infrastructure:
- docker-compose.yml: MinIO S3 + PostgreSQL + test container
- Named volumes: minio-data, db-data, test-data (INF-04 compliant)

Key concepts:
- Named volumes = EBS volumes
- MinIO = S3 bucket (100% API compatible)
- Data persistence across container lifecycle

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

labs/lab-04-storage/tests/03-persistence-test.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+# Test data persistence in database
+echo "Testing database persistence..."
+docker compose up -d db && sleep 10
+docker exec lab04-db psql -U lab04_user -d lab04_db -c "CREATE TABLE IF NOT EXISTS test (id SERIAL, data TEXT);"
+docker exec lab04-db psql -U lab04_user -d lab04_db -c "INSERT INTO test (data) VALUES ('persistent');"
+docker compose down
+docker compose up -d db && sleep 10
+RESULT=$(docker exec lab04-db psql -U lab04_user -d lab04_db -tAc "SELECT data FROM test WHERE id=1;")
+if [[ "$RESULT" == "persistent" ]]; then
+    echo "✓ Database persistence works"
+    exit 0
+else
+    echo "✗ Database persistence failed"
+    exit 1
+fi