Hollow Spiral v0.3.7

• Updated Hollow Spiral for DAI 1.9.5
• Explicitly declared Hollow Spiral as a DAI MAIN experience
• Migrated new expedition creation to DAI's native void world type
• Removed reliance on the generic Minecraft flat-world preset
• Preserved the existing experience save ID so older expeditions continue to resolve correctly
• Prepared the hollow_spire namespace for stable companion-resource-pack management
• Updated compatibility metadata for DAI 1.9.5
• Preserved all v0.3.6 dungeon-generation behavior
• Existing worlds are not regenerated by the new void-world configuration
• Retained intentional vanilla-mob encounter mode
• Includes the existing v0.3.6 vertical staircase, Coral Grotto, castle-defender, ruin, village, cavern, volcano, and environmental fixes