- Expand content to 18 zones, 72 bosses, 95 quests, 32 adventurer tiers
- Add prestige shop with 24 runestone upgrades across 5 categories
- Add PrestigeUpgrade type, data files, API routes, and frontend panel
- Fix offline earnings to include equipment and runestone multipliers
- Add offline essence calculation alongside offline gold
- Update OfflineModal to display both gold and essence earned
- Add IDEAS.md for tracking planned features
