ci: add Mendix 11.15.0 to the nightly test matrix

[ako]

What

Adds 11.15.0 to the mendix-version matrix in .github/workflows/nightly.yml, taking the nightly integration fan-out from five versions to six.

Why

11.15.0 is published on the CDN (mxbuild-11.15.0.tar.gz, HTTP 200) but nothing exercised it.

Added as a sixth entry rather than replacing 11.13.0: that version is the measured floor for timer-started workflow event sub-processes (sdk/versions/mendix-11.yaml, min_version: "11.13.0" — the constructs are TypeCacheUnknownTypeException on 11.12 and load on 11.13). Dropping it would leave the gate straddled but no job running at the floor itself.

Notes

• No other change needed — the setup mxbuild step is already parameterized on ${{ matrix.mendix-version }}, so the new job fetches its own toolchain.
• fail-fast: false is unchanged, so the new job cannot mask the others.
• Cost: one more ~857 MB mxbuild download and one more full integration run per nightly, roughly +20% wall-clock and runner minutes for this job.

Validation

CI-config only; no Go code touched. The real verification is the first nightly run — whether setup mxbuild --version 11.15.0 resolves and the integration suite passes against it.

🤖 Generated with Claude Code

[github-actions]

AI Code Review

What Looks Good

• The PR adds Mendix 11.15.0 to the nightly test matrix in .github/workflows/nightly.yml as a sixth version, preserving 11.13.0 as the measured floor for timer-started workflow event sub-processes.
• The change is purely CI configuration with no Go code modifications, aligning with the validation statement that real verification occurs during the first nightly run.
• The workflow already parameterizes the mxbuild version via ${{ matrix.mendix-version }}, so the new job will fetch the correct toolchain without additional changes.
• fail-fast: false remains unchanged, ensuring the new job cannot mask failures in other matrix entries.
• The justification clearly explains why 11.15.0 is added (to exercise a published CDN version) and why 11.13.0 is retained (as the validated minimum for specific constructs).
• The cost impact (~20% increase in wall-clock and runner minutes) is acknowledged and deemed acceptable for validation coverage.

Recommendation

Approve. The PR is a safe, scoped CI enhancement that expands test coverage to a newly available Mendix version without introducing code changes or violating project conventions. No further action is needed.

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Automated review via OpenRouter (Nemotron Super 120B) — workflow source