[contract] Add 3 Tests to invite_tests.rs (Part 2)

[Olowodarey]

📋 Overview

Expand test coverage for the invite module by adding 3 new tests (Part 2 of 2).

✅ Tasks

• Add 3 new test functions to contract/tests/invite_tests.rs
• Follow existing test patterns and helper functions
• Verify all tests pass

🧪 New Tests (3 total)

Test 1: Revoke Invite Code

#[test]
fn test_revoke_invite_code() {
    // Generate invite code
    // Revoke code
    // Try to use revoked code
    // Should fail
}

Test 2: Invite Code for Resolved Market

#[test]
fn test_use_invite_code_resolved_market() {
    // Generate invite code
    // Resolve market
    // Try to use code
    // Should fail with market expired error
}

Test 3: List All Invite Codes

#[test]
fn test_list_invite_codes_for_market() {
    // Generate multiple codes for market
    // List all codes
    // Verify all are returned with correct details
}

🔍 Verification

• All 3 tests written
• All tests pass
• Tests follow existing patterns
• No clippy warnings

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