ci: select desktop e2e specs through source reachability

[ZenAlexa]

Summary

• Derive each Desktop E2E spec's transitive repository source closure with the existing esbuild resolver.
• Pass the selected workspace-relative spec paths to Playwright through a quoted Bash array.
• Run one daily full CI execution for Electron process boundaries, generated sources, and separately bundled entry points.
• Use Playwright's list reporter to expose individual test durations in every run.

The workflow exits before Xvfb allocation when the changed files reach zero specs. Selection-authority files and full plans run all 36 spec files.

Fixes #4478

Measured effect

A replay over the latest 300 first-parent commits found 169 E2E-triggering changes. Test invocations fell from 17,914 to 7,583, a 57.67% reduction. The selection histogram was 57 zero-spec changes, 30 single-spec changes, 10 two-spec changes, one three-spec change, one seven-spec change, and 70 full plans. The scheduled escape run adds one 106-test execution per day.

Verification

• Node 24 focused planner, workflow, selector, and Windows closure suites: 82/82 passed
• Full Desktop E2E: 102 passed, 4 skipped, 6.2 minutes
• Selected e2e/sidebar-geometry.spec.ts: 2/2 passed
• npm run format:check
• npm run lint
• npm run build
• npm run typecheck
• npx knip --workspace apps/desktop
• npx knip --workspace packages/ui
• npm run check:asf-headers
• npm run check:release: 191/191 passed
• actionlint .github/workflows/ci.yml
• git diff --check

The repository-wide npm test run reached macOS environment failures in unmodified Runtime sandbox, Runtime Host fixture, and Desktop shell-env suites.

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[ZenAlexa]

e2311350 implements #4478 by selecting Desktop e2e specs from each spec's transitive source closure. Full and selection-authority changes continue to select every spec, and a nightly full run preserves broad coverage. The CI and Release Windows check suites are ready for approval; approving them will exercise the current head.