Design a clean subway map for an imaginary coastal city called 'Port Lumen'. Include 4 lines with distinct colors and names (Tide Line, Lantern Line, Harbor Line, Cliff Line) and at least 18 station names that feel local and charming (e.g., Saltmarket, Glass Pier, Old Breakwater). Show interchange icons, a simple legend, and a minimal map border. Style: modern transit schematic (like a real metro map), high contrast, perfectly legible text.