Add OSM Track Harvesting Policy and demo database initialization script

- Updated documentation to include OSM Track Harvesting Policy with details on railway types, service filters, usage filters, and geometry guardrails.
- Introduced a new script `init_demo_db.py` to automate the database setup process, including environment checks, running migrations, and loading OSM fixtures for demo data.

scripts/init_demo_db.py

@@ -0,0 +1,155 @@
+#!/usr/bin/env python3
+"""
+Initialize the database with demo data for the Rail Game.
+
+This script automates the database setup process:
+1. Validates environment setup
+2. Runs database migrations
+3. Loads OSM fixtures for demo data
+
+Usage:
+    python scripts/init_demo_db.py [--dry-run] [--region REGION]
+
+Requirements:
+- Virtual environment activated
+- .env file configured with DATABASE_URL
+- PostgreSQL with PostGIS running
+"""
+
+import argparse
+import os
+import subprocess
+import sys
+from pathlib import Path
+
+try:
+    from dotenv import load_dotenv
+    load_dotenv()
+except ImportError:
+    print("WARNING: python-dotenv not installed. .env file will not be loaded automatically.")
+    print("Install with: pip install python-dotenv")
+
+
+def check_virtualenv():
+    """Check if we're running in a virtual environment."""
+    if not hasattr(sys, 'real_prefix') and not (hasattr(sys, 'base_prefix') and sys.base_prefix != sys.prefix):
+        print("ERROR: Virtual environment not activated. Run:")
+        print("  .venv\\Scripts\\Activate.ps1  (PowerShell)")
+        print("  source .venv/bin/activate     (Bash/macOS/Linux)")
+        sys.exit(1)
+
+
+def check_env_file():
+    """Check if .env file exists."""
+    env_file = Path('.env')
+    if not env_file.exists():
+        print("ERROR: .env file not found. Copy .env.example to .env and configure:")
+        print("  Copy-Item .env.example .env  (PowerShell)")
+        print("  cp .env.example .env          (Bash)")
+        sys.exit(1)
+
+
+def check_database_url():
+    """Check if DATABASE_URL is set in environment."""
+    database_url = os.getenv('DATABASE_URL')
+    if not database_url:
+        print("ERROR: DATABASE_URL not set. Check your .env file.")
+        sys.exit(1)
+    print(f"Using database: {database_url}")
+
+
+def run_command(cmd, cwd=None, description=""):
+    """Run a shell command and return the result."""
+    print(f"\n>>> {description}")
+    print(f"Running: {' '.join(cmd)}")
+    try:
+        result = subprocess.run(cmd, cwd=cwd, check=True,
+                                capture_output=True, text=True)
+        if result.stdout:
+            print(result.stdout)
+        return result
+    except subprocess.CalledProcessError as e:
+        print(f"ERROR: Command failed with exit code {e.returncode}")
+        if e.stdout:
+            print(e.stdout)
+        if e.stderr:
+            print(e.stderr)
+        sys.exit(1)
+
+
+def run_migrations():
+    """Run database migrations using alembic."""
+    run_command(
+        ['alembic', 'upgrade', 'head'],
+        cwd='backend',
+        description="Running database migrations"
+    )
+
+
+def load_osm_fixtures(region, dry_run=False):
+    """Load OSM fixtures for demo data."""
+    cmd = ['python', '-m', 'backend.scripts.osm_refresh', '--region', region]
+    if dry_run:
+        cmd.append('--no-commit')
+        description = f"Loading OSM fixtures (dry run) for region: {region}"
+    else:
+        description = f"Loading OSM fixtures for region: {region}"
+
+    run_command(cmd, description=description)
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="Initialize database with demo data")
+    parser.add_argument(
+        '--region',
+        default='all',
+        help='OSM region to load (default: all)'
+    )
+    parser.add_argument(
+        '--dry-run',
+        action='store_true',
+        help='Dry run: run migrations and load fixtures without committing'
+    )
+    parser.add_argument(
+        '--skip-migrations',
+        action='store_true',
+        help='Skip running migrations'
+    )
+    parser.add_argument(
+        '--skip-fixtures',
+        action='store_true',
+        help='Skip loading OSM fixtures'
+    )
+
+    args = parser.parse_args()
+
+    print("Rail Game Database Initialization")
+    print("=" * 40)
+
+    # Pre-flight checks
+    check_virtualenv()
+    check_env_file()
+    check_database_url()
+
+    # Run migrations
+    if not args.skip_migrations:
+        run_migrations()
+    else:
+        print("Skipping migrations (--skip-migrations)")
+
+    # Load fixtures
+    if not args.skip_fixtures:
+        load_osm_fixtures(args.region, args.dry_run)
+    else:
+        print("Skipping fixtures (--skip-fixtures)")
+
+    print("\n✅ Database initialization completed successfully!")
+    if args.dry_run:
+        print("Note: This was a dry run. No data was committed to the database.")
+    else:
+        print("Demo data loaded. You can now start the backend server.")
+
+
+if __name__ == '__main__':
+    main()