ci(cd-rust-cua-driver): pin macOS build to macos-26 runner

[f-trycua]

Why

v0.3.0 CD failed on darwin-universal:

```
.../apple-metal-0.8.7/swift-bridge/Sources/AppleMetalBridge/State.swift:128:
error: cannot find 'MTLSamplerReductionMode' in scope
error: value of type 'MTLSamplerDescriptor' has no member 'reductionMode'
error: value of type 'MTLSamplerDescriptor' has no member 'lodBias'
```

Dep chain:

```
cua-driver → platform-macos → screencapturekit v6.0.1 → apple-metal v0.8.7
```

apple-metal v0.8.7 uses #available(macOS 26.0, *)-guarded Swift code that references symbols only present in the macOS 26 SDK. The macos-15 runner ships a macOS 15 SDK, so the Swift bridge fails to compile even though the code is gated by if #available.

screencapturekit = "6" was added in #1720 to ship the native ScreenCaptureKit recording backend.

Change

Single line: runs-on: macos-15 → runs-on: macos-26 in the build-macos-universal job, plus an inline comment recording the why for future me.

macOS 26 runners are available now per actions/runner-images#13739.

Out of scope

The Swift CI/CD workflows (cd-swift-cua-driver.yml, cd-swift-lume.yml, ci-swift-*.yml) also pin macos-15. Leaving them on macos-15 for now — they don't share the apple-metal transitive and have their own release cadence.

Test plan

• Workflow YAML still parses (no syntax changes beyond the runner label + comment)
• After merge: re-trigger bump for cua-driver-rs (patch → v0.3.1) and confirm darwin-universal job now passes, release publishes all 6 platform asset sets.

Summary by CodeRabbit

• Chores
  • Updated macOS build environment from macOS 15 to macOS 26 for the universal binary build.

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
docs	Ignored	Preview	May 27, 2026 2:19pm

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: e1e156c6-9598-41e8-9b16-595fb5f2457d

📥 Commits

Reviewing files that changed from the base of the PR and between 38817f1 and 18997fa.

📒 Files selected for processing (1)

• .github/workflows/cd-rust-cua-driver.yml

---

📝 Walkthrough

Walkthrough

GitHub Actions workflow configuration updated to upgrade the macOS universal build job runner from macos-15 to macos-26. Comments clarify that macOS 26 is required for ScreenCaptureKit Swift bridge symbol availability.

Changes

macOS Runner Configuration

Layer / File(s)	Summary
macOS 26 runner and SDK documentation .github/workflows/cd-rust-cua-driver.yml	Runner version updated from macos-15 to macos-26 with expanded comments explaining the dependency on macOS 26 SDK for ScreenCaptureKit Swift bridge symbols.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

🐰 A runner jumps from fifteen to twenty-six,
For ScreenCaptureKit, a macOS fix,
Swift symbols flow from the newer SDK's ground,
Where universal builds find their macOS sound! 🍎

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically summarizes the main change: updating the macOS build runner to macos-26, which directly addresses the core issue (dependency on macOS 26 SDK symbols).
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch ci/macos-26-runner

---

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