feat: add copyable failure transcripts

[itzptk]

Summary

• Adds a shared failure transcript formatter for failed Homebrew jobs.
• Shows the transcript in failed command-progress diagnostics and exposes a Transcript action in job history.
• Copies the exact formatted transcript text from both UI paths.

Closes #30

Verification

• npm test -- --include src/app/shared/job-failure-transcript.spec.ts --include src/app/features/history/history-view/history-view.component.spec.ts --include src/app/components/ux/command-progress-drawer/command-progress-drawer.component.spec.ts — passed: 3 files, 11 tests.
• npm run test:all — passed: Angular 115 files / 256 tests; Node Vitest 15 files / 116 tests.
• npm run build — passed: Angular production build and Electron tsup build succeeded.

Notes

• Full Angular suite still emits the existing dark-mode media-query listener stderr warnings in src/app/app.spec.ts, but all tests pass.