test: add a testnet end-to-end smoke test for the full campaign lifecycle

[JamesVictor-O]

Background

All existing test coverage runs against soroban_sdk::testutils::Env — a mocked, in-process host environment. That's the right tool for fast unit/logic testing (and this repo has a lot of good coverage there now), but it doesn't exercise real network semantics: actual transaction submission, real stellar contract invoke argument encoding, real TTL/rent behavior over ledger time, real Stellar Asset Contract token behavior, or the actual deploy.sh script (#23) that's meant to be how these contracts get deployed in practice.

Right now nobody has verified that a freshly-deploy.sh'd pair of contracts on testnet can actually complete a full campaign lifecycle end-to-end through the real CLI — only that the Rust logic is correct in a mock.

Expected behaviour

A script (e.g. scripts/testnet-smoke-test.sh, or a justfile/Makefile target) that, against a real testnet deployment:

1. Runs deploy.sh (or assumes contracts are already deployed and takes their IDs as input)
2. Funds two or three testnet accounts via friendbot
3. Drives a full campaign lifecycle purely through stellar contract invoke calls: create_campaign → fund_campaign → apply_to_campaign → approve_creator → submit_proof → approve_submission → claim_payment
4. Asserts on-chain balances moved as expected (via stellar contract invoke -- get_campaign / a Horizon balance query)

This doesn't need to run on every CI push (testnet dependency, funded accounts, network flakiness), but should be runnable on demand — e.g. a manually-triggered GitHub Actions workflow, or just documented as a pre-release checklist item — so there's some point before a mainnet deployment where the actual deployed artifact gets exercised, not just the source.

Files

• New script under scripts/ or similar
• Possibly a new, manually-triggered CI workflow

Acceptance criteria

• A script exists that drives a full campaign lifecycle against a real (testnet) deployment purely through the CLI, not cargo test
• It fails loudly (non-zero exit, clear error) if any step's on-chain result doesn't match expectations
• Documented in the README or docs/ARCHITECTURE.md as part of the pre-deployment checklist

[SudiptaPaul-31]

Hey Maintainer!!! My name is Sudipta Paul a very old contributor of GrantFox and other platform having quite a lot of experience in open source and working with full stack issues as well as very much proficient in writing contracts and would love to work on this issue and contribute to your project, May I be assigned to this task

[grantfox-oss]

🦊 GrantFox — @SudiptaPaul-31 has been assigned to this issue as part of the Third Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #47)
2. Your PR will be reviewed by the Ads-Bazaar maintainers

Good luck! Track your progress on GrantFox.