feat(shade): event ticketing — payment, minting, royalty resale

[Depo-dev]

Summary

Implements the Shade contract's event ticketing system end to end: paid event creation, on-chain payment via Shade, NFT-style ticket minting, and royalty-enforced secondary resale.

Closes #246 (Event Creation Logic), #247 (Shade Payment Integration), #248 (Ticket Minting Logic), #254 (Royalty Fee on Resale).

What landed

• Event creation (Implement Event Creation Logic #246): extended Event with event_date and royalty_bps. create_event validates ticket_price > 0, capacity > 0, royalty_bps <= 10_000, event_date >= ledger_timestamp, and that the token is platform-accepted.
• Payment integration (Integrate Shade Payment Gateway for Ticket Purchases #247): purchase_ticket now actually transfers ticket_price - fee to the merchant account and the fee to the platform account, then records merchant analytics — using the same primitives as pay_invoice. Validations run before any state mutation.
• Ticket minting (Implement Ticket Minting Logic #248): introduced Ticket { id, event_id, owner, minted_at }. Each purchase mints a unique ticket, persists it under DataKey::Ticket(id), and indexes it per-event (EventTickets) and per-user (UserTickets).
• Resale royalty (Implement Royalty Fee Calculation on Ticket Resale #254): resell_ticket(seller, buyer, ticket_id, resale_price) splits the resale price into royalty = price * royalty_bps / 10_000 to the organizer and the remainder to the seller, then transfers ownership. Royalty math uses checked_mul to catch overflow.
• Errors: 10 new variants (EventNotFound, EventSoldOut, InvalidCapacity, InvalidEventDate, InvalidRoyaltyBps, TicketNotFound, NotTicketOwner, TicketEventMismatch, InvalidResalePrice — plus reuse of existing payment errors).
• Events emitted: EventCreatedEvent, TicketPurchasedEvent, TicketResoldEvent.

Tests

contracts/shade/src/tests/test_event_tickets.rs covers:

• ✅ Create event stores all fields
• ✅ Reject zero price / zero capacity / royalty > 100% / past event date
• ✅ Purchase moves funds and mints a ticket; user index updated; sold counter incremented
• ✅ Platform fee routed correctly when configured
• ✅ Sold-out rejection
• ✅ Missing-event rejection
• ✅ Resale splits royalty to organizer + remainder to seller; ownership and indexes updated
• ✅ Zero-royalty resale pays seller in full
• ✅ Reject non-owner seller / zero resale price / unknown ticket id

Repo health fixes bundled in (main was red on cargo check)

These were already broken on main before this PR — folding the minimal fixes in so the lib compiles and CI can run:

• components/admin.rs: replaced std::vec::Vec (the crate is #![no_std]) with an in-place insertion sort on soroban_sdk::Vec.
• shade.rs: removed four impl methods (get_daily_volume, get_weekly_volume, get_merchant_daily_volume, get_merchant_weekly_volume) that were not declared in ShadeTrait and delegated to nonexistent admin_component functions.
• interface.rs: imported PaymentPayload (used by validate_payment_payload but missing from the use list).
• types.rs: moved FiatPricing above Invoice so the macro expansion for Option<FiatPricing> resolves cleanly.

Test plan

• cargo check -p shade clean (was failing on main pre-PR)
• CI runs cargo test --workspace --all-features on Linux
• CI clippy + fmt

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[codebestia]

LGTM!
Thank you for your contribution!