[codex] Prepare Dimmerly 1.0.2 release

[olujicz]

Summary

• Polish the menu bar panel glass and scrollbar styling for the macOS menu surface.
• Stabilize the scroll-style configurator so AppKit delayed scroller normalization does not undo the intended persistent scrollbar settings.
• Gate the macOS 26 .glassProminent button style so older SDKs still compile while newer toolchains use the Tahoe style.
• Move required PR CI jobs to the macos-26 GitHub Actions runner and update BUILDING.md to match.
• Prepare the 1.0.2 release by updating CHANGELOG.md, MARKETING_VERSION, and CURRENT_PROJECT_VERSION.

Root Cause

The initial CI failure happened because the PR used .glassProminent, which local Xcode 26 can compile but the previous CI baseline, Xcode 16.4, cannot resolve. The style is now wrapped in a compiler gate and runtime availability check.

After moving CI to macos-26, the test job exposed a separate brittle assertion: a detached NSScrollView can have scrollerStyle normalized by AppKit after a run-loop pass. The direct scroll-style unit test still verifies .overlay; the configurator test now checks the persistent settings that prove the configurator found and styled the scroll view.

Release Notes

This prepares Dimmerly 1.0.2 with build number 3. Per documentation/RELEASE.md, this PR does not create or push the v1.0.2 release tag. After merge, run the manual Release workflow for the 1.0.2 release candidate and complete RC QA before tagging.

Validation

Local:

• actionlint .github/workflows/ci.yml
• just format-check
• just lint
• just test
• just build-appstore
• just build-release from the release-prep pass
• Verified the built Release app reports version 1.0.2 and build 3.

GitHub Actions:

• CI run 28535425519 passed on macos-26: workflow-lint, format, lint, test, and build-appstore.