[Audit] Duplicate, uncached CI job execution across two workflows

[K1NGD4VID]

Filed from the second-wave repository audit (issue 50/100). See the audit summary for full category context.

• Location: .github/workflows/pr-test-gate.yml (fully duplicates ci.yml's contracts-test and backend-test jobs)
• Problem: Both workflows trigger on pull_request to main and run the same test suites; pr-test-gate.yml's Rust job additionally has no Swatinem/rust-cache step (present in ci.yml), so contracts are rebuilt from a cold cache on every PR in addition to the already-cached build in ci.yml.
• Evidence: Side-by-side job definitions in the two workflow files cover identical test scopes.
• Suggested implementation: Consolidate into one workflow (or have pr-test-gate.yml depend on/reuse ci.yml's job results via workflow_run/reusable workflows) and add the missing rust-cache step if any duplication remains.
• Acceptance criteria: Contracts/backend tests run exactly once per PR push, verified by comparing total CI minutes before/after.
• Difficulty: M
• Expected impact: Meaningfully reduces CI cost and PR feedback latency (two full Postgres+Prisma+Vitest+Cargo runs currently happen per push).

[chukwunazannakenyi-netizen]

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

Hi maintainer I would like to work on this issue

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

[ponmileleke54-dev]

@ponmileleke54-dev has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

I would like to work on this

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[Rafiat30]

@Rafiat30 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

i would love to work on this

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[solidsole]

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

Please assign this issue to me .... ill begin immediately and wont disappoint...

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[ayomustap]

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

Hi maintainer, Kindly assign. I can fix this issue

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[drips-wave]

Congratulations, @ponmileleke54-dev! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

🧑‍💻 @ponmileleke54-dev: 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.

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