Add complete financial fraud detection database with Docker, schema, data generation, and SQL exercises

- Docker setup with PostgreSQL 16 and DB-UI web interface
- Comprehensive 20+ table schema with fraud detection patterns
- Idempotent shell scripts for data generation (no Python dependency)
- Realistic geographic data (100 US cities, 210 world cities)
- 5M+ transactions with embedded fraud patterns (velocity, geographic, structuring, etc.)
- Progressive SQL exercises from beginner to advanced fraud detection
- Complete documentation and quick start guide
- Setup and verification scripts

docs/QUICKSTART.md

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+# Quick Start Guide
+
+## 🚀 Get Up and Running in 5 Minutes
+
+### Step 1: Start Docker Containers (1 minute)
+
+```bash
+# From the project root directory
+docker-compose up -d
+```
+
+**What this does:**
+- Starts PostgreSQL 16 database
+- Starts DB-UI web interface
+- Creates network and volumes
+
+**Verify it's running:**
+```bash
+docker-compose ps
+```
+
+You should see both `fraud_detection_db` and `fraud_detection_ui` running.
+
+---
+
+### Step 2: Initialize Database Schema (1 minute)
+
+```bash
+# Make script executable (first time only)
+chmod +x scripts/setup-database.sh
+
+# Run setup
+./scripts/setup-database.sh
+```
+
+**What this does:**
+- Creates all 20+ tables
+- Sets up indexes and constraints
+- Loads reference data (countries, merchant categories, etc.)
+
+**Expected output:**
+```
+✓ PostgreSQL is ready
+✓ Creating tables, indexes, and constraints
+✓ Loading reference data
+✓ Database setup completed successfully!
+```
+
+---
+
+### Step 3: Generate Test Data (15-30 minutes)
+
+```bash
+# Make script executable (first time only)
+chmod +x data/generate_data.sh
+
+# Run data generation
+./data/generate_data.sh
+```
+
+**What this does:**
+- Generates 100,000 customers
+- Creates 150,000 accounts
+- Generates 5,000,000 transactions
+- Creates fraud patterns and alerts
+
+**⏱️ Time estimate:**
+- Fast machine (SSD, 16GB RAM): ~15 minutes
+- Average machine: ~20-25 minutes
+- Slower machine: ~30 minutes
+
+**You can monitor progress:**
+The script shows progress for each step:
+```
+[1/9] Loading geographic reference data...
+[2/9] Generating Customers...
+[3/9] Generating Accounts...
+...
+```
+
+---
+
+### Step 4: Access the Database
+
+#### Option A: DB-UI Web Interface (Recommended for Beginners)
+
+1. Open your browser to: **http://localhost:3000**
+2. You'll see the database tables in the sidebar
+3. Click any table to browse data
+4. Use the "Custom SQL" tab to run queries
+
+**Features:**
+- Visual table browser
+- SQL query editor with syntax highlighting
+- Export results to CSV
+- Schema introspection
+
+#### Option B: Command Line (psql)
+
+```bash
+docker exec -it fraud_detection_db psql -U fraud_analyst -d fraud_detection
+```
+
+**Quick commands:**
+```sql
+-- List all tables
+\dt
+
+-- Describe a table
+\d customers
+
+-- Run a query
+SELECT COUNT(*) FROM transactions;
+
+-- Exit
+\q
+```
+
+#### Option C: Your Favorite SQL Client
+
+**Connection Details:**
+```
+Host:     localhost
+Port:     5432
+Database: fraud_detection
+Username: fraud_analyst
+Password: SecurePass123!
+```
+
+**Popular clients:**
+- DBeaver (free, cross-platform)
+- pgAdmin (free, PostgreSQL-specific)
+- DataGrip (paid, JetBrains)
+- TablePlus (paid, macOS/Windows)
+
+---
+
+## 🎓 Your First Queries
+
+### 1. Check Data Counts
+
+```sql
+-- How many customers?
+SELECT COUNT(*) FROM customers;
+
+-- How many transactions?
+SELECT COUNT(*) FROM transactions;
+
+-- How many fraud alerts?
+SELECT COUNT(*) FROM alerts WHERE status = 'OPEN';
+```
+
+### 2. Find High-Risk Customers
+
+```sql
+SELECT 
+    customer_id,
+    first_name,
+    last_name,
+    email,
+    risk_score
+FROM customers
+WHERE risk_score > 80
+ORDER BY risk_score DESC
+LIMIT 10;
+```
+
+### 3. View Recent Transactions
+
+```sql
+SELECT 
+    transaction_id,
+    account_id,
+    amount,
+    transaction_date,
+    is_flagged
+FROM transactions
+ORDER BY transaction_date DESC
+LIMIT 20;
+```
+
+### 4. Find Flagged Transactions
+
+```sql
+SELECT 
+    t.transaction_id,
+    t.amount,
+    t.fraud_score,
+    t.flagged_reason,
+    c.first_name,
+    c.last_name
+FROM transactions t
+JOIN accounts a ON t.account_id = a.account_id
+JOIN customers c ON a.customer_id = c.customer_id
+WHERE t.is_flagged = TRUE
+ORDER BY t.fraud_score DESC
+LIMIT 10;
+```
+
+---
+
+## 📚 Next Steps
+
+### Start Learning SQL
+
+1. **Begin with basics:** `exercises/01-basic-queries/README.md`
+2. **Progress through levels:** Work through exercises 01-06
+3. **Practice fraud detection:** `exercises/06-fraud-detection/README.md`
+
+### Explore the Data
+
+```sql
+-- What countries are represented?
+SELECT country_name, COUNT(*) as customer_count
+FROM customers c
+JOIN countries co ON c.country_id = co.country_id
+GROUP BY country_name
+ORDER BY customer_count DESC;
+
+-- What are the top merchant categories?
+SELECT mc.category_name, COUNT(*) as transaction_count
+FROM transactions t
+JOIN merchants m ON t.merchant_id = m.merchant_id
+JOIN merchant_categories mc ON m.category_id = mc.category_id
+GROUP BY mc.category_name
+ORDER BY transaction_count DESC;
+
+-- How many fraud cases by type?
+SELECT ft.fraud_name, COUNT(*) as case_count
+FROM fraud_cases fc
+JOIN fraud_types ft ON fc.fraud_type_id = ft.fraud_type_id
+GROUP BY ft.fraud_name
+ORDER BY case_count DESC;
+```
+
+---
+
+## 🔧 Troubleshooting
+
+### Database won't start
+
+```bash
+# Check logs
+docker-compose logs postgres
+
+# Restart containers
+docker-compose restart
+```
+
+### Can't connect to database
+
+```bash
+# Check if PostgreSQL is ready
+docker exec fraud_detection_db pg_isready -U fraud_analyst
+
+# Check port is not in use
+netstat -an | grep 5432
+```
+
+### Data generation fails
+
+```bash
+# Check disk space
+df -h
+
+# Check memory
+free -h
+
+# Try with smaller dataset
+# Edit data/generate_data.sh and reduce:
+NUM_CUSTOMERS=10000
+NUM_TRANSACTIONS=500000
+```
+
+### Reset everything
+
+```bash
+# Stop and remove everything
+docker-compose down -v
+
+# Start fresh
+docker-compose up -d
+./scripts/setup-database.sh
+./data/generate_data.sh
+```
+
+---
+
+## 💡 Tips
+
+1. **Use DB-UI for exploration** - Great for browsing and understanding the schema
+2. **Use psql for practice** - Best for learning SQL commands
+3. **Start simple** - Begin with basic SELECT queries before complex joins
+4. **Check the exercises** - They're designed to build your skills progressively
+5. **Experiment** - The database is yours to explore and learn from!
+
+---
+
+## 🎯 Learning Goals
+
+After completing this tutorial, you'll be able to:
+
+- ✅ Write complex SQL queries
+- ✅ Understand database relationships
+- ✅ Detect fraud patterns in data
+- ✅ Use window functions and CTEs
+- ✅ Optimize queries with indexes
+- ✅ Investigate financial crimes
+
+---
+
+**Ready to start? Head to `exercises/01-basic-queries/README.md`!** 🚀
+