feat(contracts): resource_credits queries + expiry + tests + event_ticketing scaffold

[Tinna23]

Summary

Implements four issues assigned to @Tinna23 in a single branch.

Closes #769
Closes #770
Closes #771
Closes #772

---

Changes

CT-05 — Credit balance & supply query functions (#769)

• get_balance(env, member) -> u128 — returns member's credit balance (0 if unset)
• get_total_supply(env) -> u128 — returns total credits in circulation
• get_admin(env) -> Result<Address, Error> — returns current admin
• All three are read-only (no state mutation)

CT-06 — Credit expiry mechanism (#770)

• CreditBalance in types.rs gains expires_at: Option<u64>
• mint_credits accepts optional expires_at: Option<u64>
• transfer_credits returns Error::CreditsExpired when sender's credits are past expiry
• spend_credits returns Error::CreditsExpired when credits are expired
• is_expired(env, member) -> bool query added

CT-07 — Test suite for resource_credits (#771)

14 tests in src/test.rs covering:

• initialize sets admin and rejects re-initialization
• mint_credits increases balance and total supply; rejects non-admin
• transfer_credits moves credits correctly; fails with InsufficientBalance
• spend_credits reduces balance and supply; fails with InsufficientBalance
• Expired credits cannot be transferred or spent
• get_balance returns 0 for unknown members
• get_admin and get_total_supply return correct values

CT-08 — Scaffold event_ticketing contract (#772)

New contract at contracts/sandbox/event_ticketing/:

• Cargo.toml with soroban-sdk workspace dependency
• src/types.rs: Event, Ticket, EventStatus, TicketStatus
• src/errors.rs: 10 error variants (AdminNotSet, AlreadyInitialized, Unauthorized, EventNotFound, TicketNotFound, EventSoldOut, EventNotActive, InvalidTimeRange, InvalidPrice, TicketNotTransferable)
• src/lib.rs: DataKey enum (Admin, PaymentToken, Event(String), EventList, Ticket(String), EventTickets(String), OwnerTickets(Address)) + initialize stub

Workspace

• Both sandbox/resource_credits and sandbox/event_ticketing added to contracts/Cargo.toml workspace members

[vercel]

@Tinna23 is attempting to deploy a commit to the naijabuz's projects Team on Vercel.

A member of the Team first needs to authorize it.

[drips-wave]

@Tinna23 Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits