fix(desktop): preserve checkpoint controls at mixed DPI

[Qiyuanqiii]

Summary

• retain workspaceCheckpointControlEnabled through Desktop bootstrap, connection-store lifecycle, App, and CyberAgentClient
• keep Run-view tab labels at intrinsic width so the existing horizontal tab scroller works instead of labels overlapping at high DPI
• add the completed Windows 11 dual-display mixed-DPI sign-off and exact 1024×768 evidence for issue test(desktop): 完成多显示器混合 DPI 与交互式 UI 签字 #85

Verification

Formal candidate:

• revision: c531bd2ed96b9c9f5210ab86358c15d647b5e984
• version: v0.1.0-issue85-r4
• EXE SHA-256: 9b42e3e57b85954d3add54aa18d8a795738253b60f1c2370594956a9fe957dce
• source tree: clean; reproducible build: pass

Automated checks passed:

• npm audit: 0 vulnerabilities
• frontend: 65 files / 288 tests
• frontend production build
• Go Desktop, web UI, and command tests
• Windows compatibility check
• cold start, second instance, normal exit, and kill/reopen

Manual sign-off passed on Windows 11 build 26200 / WebView2 151.0.4129.93:

• Extend mode, 2560×1600 at 150% plus 3840×2160 at 200%
• 150% → 200% → 150% without candidate restart
• exact 1024×768 logical window verification
• Light/Dark/Acrylic, zh/en, sidebar resize/collapse, focused input, long Markdown, Live Activity, Approvals, Settings/Full CDP
• Checkpoint timeline, Preview Rewind, explicit Rewind confirmation/result, and independent Fork
• no overlap, truncation, focus loss, blanking, or abnormal scaling

Evidence: result-r4.json and evidence index.

The Advanced Git rows added later by #117 / #120 are intentionally outside this issue's original sign-off scope.

Closes #85