test(desktop): prune duplicate Electron journeys

[jackwener]

Summary

• remove five low-signal Electron specs whose behavior is already owned by source contracts, Storybook, alignment smoke, or service/unit tests
• collapse provider, floating-layer, settings, bot, quote, send, and sidebar coverage to representative cross-boundary journeys and failure paths
• remove the orphaned Playwright permission fixture and stale references to deleted specs

Measured impact

• Electron E2E: 91 to 58 tests, about 36% fewer app launches
• E2E source: 4,920 to 2,866 lines, about 42% smaller
• CI-like one-worker E2E: historical 6m19s to 2.8m on this worktree, about 56% faster

Verification

• npm run build
• npm run typecheck
• npm run lint
• npm run format:check
• npm run test:scripts
• 223 targeted replacement-layer unit/contract tests
• full Electron E2E with 4 workers: 58 passed in 1.8m
• full Electron E2E with CI=1: 58 passed in 2.8m