[CONTRACT] Build and publish the WASM artifact in Contract CI

[Cedarich]

Complexity: Trivial (100)

Description
.github/workflows/contract-ci.yml installs the wasm32-unknown-unknown target and then never uses it — the job runs cargo fmt, cargo clippy, and cargo test only. A change that compiles for the host but breaks the no_std wasm build passes CI today. Add a release wasm build, report the resulting binary size, and upload it as a workflow artifact.

Acceptance Criteria

• Contract CI runs cargo build --target wasm32-unknown-unknown --release and fails the job on error
• The built .wasm is uploaded as a workflow artifact for the commit
• The job prints the wasm file size so size regressions are visible in the PR checks
• A size ceiling is enforced (or a warning is emitted) so accidental bloat is caught early
• The workflow name in the artifact matches the actual crate output name produced by Cargo.toml

[escaprt]

@escaprt has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

hello can you give me one issue pls

ℹ️ Repo Maintainers: To accept this application, review their application or assign @escaprt to this issue.

[drips-wave]

Congratulations, @Flourigax! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

🧑‍💻 @Flourigax: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

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