Fix pgAdmin email validation and add SQL verification queries

PGADMIN FIX:

- Changed email from admin@businessanalytics.local to admin@example.com

- pgAdmin rejects .local domains as invalid email addresses

- Updated all documentation with correct email

SETUP VERIFICATION:

- Added 5 SQL verification queries to setup-database.sh

- Query 1: Sample countries (top 5)

- Query 2: Sample merchant categories (top 5)

- Query 3: All transaction types with descriptions

- Query 4: All fraud types ordered by severity

- Query 5: All customer segments with descriptions

BENEFITS:

- Users can immediately see that data was loaded correctly

- Provides visual confirmation of schema setup

- Shows sample data structure before generating full dataset

- Helps troubleshoot setup issues early

docs/QUICKSTART.md

@@ -142,7 +142,7 @@ The script shows progress for each step:
 
 1. Open your browser to: **http://localhost:3000**
 2. **Login:**
-   - Email: `admin@businessanalytics.local`
+   - Email: `admin@example.com`
    - Password: `SecurePass123!`
 3. **First time setup - Add Server:**
    - Click "Add New Server"