Implement a comprehensive solar system progression framework enabling players to unlock and travel to different planets. Includes:

• PlanetManager to coordinate planet-specific environments, lighting, and dynamic effects
• Nine planet environment modules (Earth, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto) with unique visual characteristics
• ProgressionSystem for tracking unlocked planets, launches, and missions
• TravelSystem for coordinating launch destinations and planet unlocking
• DestinationSelector modal UI for selecting target planets before launch
• LeftProgressPanel showing solar system progress, active planet, and unlock status
• Updated MainMenu to display solar system grid instead of simple navigation
• Planets unlock when player successfully launches to them
• Each planet has distinct environments: lighting, fog, vegetation/terrain, atmospheric effects