fix: missing smoke test for contract deployment — CI doesn't verify contracts deploy successfully

[sanmipaul]

Bug

`.github/workflows/ci.yml` builds and tests the Soroban contracts but does not perform an actual deployment smoke test to Stellar testnet. It's possible for contracts to pass all local unit tests but fail to deploy due to:

• WASM binary exceeding size limits
• Missing or incorrect contract metadata
• Incompatible Soroban SDK version with the current testnet
• Missing `#![no_std]` attribute causing deployment rejection

Fix

Add a deployment smoke test job that runs on PRs targeting `main`:

```yaml
deploy-smoke-test:
runs-on: ubuntu-latest
needs: [build, test]
steps:
- name: Deploy invoice contract to testnet
run: |
soroban contract deploy
--wasm target/wasm32-unknown-unknown/release/invoice.wasm
--source ${{ secrets.TESTNET_DEPLOYER_SECRET }}
--network testnet
--fee 1000000
id: deploy-invoice

- name: Smoke test — call get_invoice on deployed contract
  run: |
    soroban contract invoke \
      --id ${{ steps.deploy-invoice.outputs.contract-id }} \
      --fn get_invoice \
      --arg 999 \  # non-existent invoice
      --network testnet
    # Should return InvoiceError::NotFound — verify it doesn't crash

```

Acceptance Criteria

• Deployment smoke test job added to CI (runs on PR to main)
• All 3 contracts deployed and verified against testnet
• At least one view function called per contract post-deployment
• Deployed contract IDs output as job artifacts for debugging
• Job uses a dedicated `TESTNET_DEPLOYER_SECRET` GitHub secret (not main admin key)

References

• `.github/workflows/ci.yml`
• `contracts/`

[Nemenwq]

@Nemenwq has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hello maintainer, please can i work on this? ETA: 6hours

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[oscar24357]

@oscar24357 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hello maintainer, I would love to work on this issue, can you please assign me to it

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[Michael997glitch]

@Michael997glitch has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

i've resolved similar problems in the past and am confident i can implement a clean, efficient fix quickly, if am given the opportunity below are the details of the work i want you to implement.

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[Oluwasuyi-Oluwatimilehin-Daniel]

@Oluwasuyi-Timilehin has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hello please assign me to this task. I would get started immediately

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[Malcolm-Wander]

@Malcolm-Wander has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hello maintainer,I’d love to work on this issue please…promise to do bad accurate and swift job,thank you.

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[drips-wave]

Congratulations, @Nemenwq! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

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[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign campaign!

@Nemenwq's PR #815 was approved and merged by @sanmipaul.

🏆 @Nemenwq: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (436 total points). Track your full progress on GrantFox.

👏 Great work, @Nemenwq! Keep contributing to astera-hq.

[drips-wave]

This issue has been completed by @Nemenwq as part of the Stellar Wave Program's 6th Wave 🥳

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