test: add fuzz tests and increase coverage

[dadadave80]

Summary

• Add 31 foundry fuzz tests across Factory, Marketplace, CheckIn, and Ticket test files covering fee calculations, payment accounting, refund timing, buyer accumulation, and ticket creation validation
• Add 52 coverage tests for previously untested revert paths and edge cases including empty name/URI, sold out, max tickets per user, purchase time checks, admin access control, ERC721 interface support, and royalty info

Test plan

• All 176 tests pass (forge test)
• Fuzz tests run 10,000 iterations each per foundry.toml config
• Verify CI passes on remote