feat(screenshot): add --with-frame for full macOS window capture

[Shadow-Azure]

Summary

• Add --with-frame flag to sandbox screenshot command for capturing the full macOS window (titlebar, traffic lights, tab bar, status bar)
• Default mode captures terminal-only content via Renderer WebSocket → xterm.js captureToPng()
• --with-frame mode captures full Electron window via ScreenCaptureKit
• Two capture paths: renderer-based (terminal only) vs ScreenCaptureKit (full window)

Architecture

CLI screenshot --id <id>
  → daemon HTTP GET /sandbox/{id}/screenshot?with_frame=true
  → if with_frame: request_renderer_screenshot_with_frame() → switch tab → ScreenCaptureKit → switch back
  → if default: request_renderer_screenshot() → renderer WebSocket → xterm.js captureToPng()
  → fallback: ScreenCaptureKit if renderer unavailable

Bug Fixes

1. Default screenshots showed window frame instead of terminal-only

Problem: After adding --with-frame, the default screenshot mode also showed the full macOS window frame.

Root cause: request_renderer_screenshot() function was removed during --with-frame implementation, causing all screenshots to fall back to ScreenCaptureKit which captures the entire window.

Fix: Restored request_renderer_screenshot() function and added capture_request handler to renderer.

2. White border at bottom of --with-frame screenshots

Problem: --with-frame screenshots had a white border/shadow at the bottom of the window.

Root cause: ScreenCaptureKit captures window shadows by default.

Fix: Added .with_ignores_shadows_single_window(true) to SCStreamConfiguration in capture_window().

Test Results

Mode	Content	Size
Default	Pure terminal content (zn-ice@MacBook-Neo ~ %)	18,895 B
--with-frame	Full macOS window with titlebar, traffic lights, tab bar, status bar	36,144 B

Test plan

• cargo check --all-targets passes
• Default mode captures terminal-only content
• --with-frame mode captures full macOS window
• No white border in --with-frame screenshots
• Per-tab screenshots for different sandboxes (requires renderer WebSocket connection)

🤖 Generated with Claude Code

[github-actions]

🔒 门禁检查结果

检查项	状态
Rust 格式化	✅ success
Rust Clippy	✅ success
Rust 测试 & 覆盖率	✅ success
前端测试 & 覆盖率	✅ success
安全检查	✅ success

Rust 测试覆盖率

指标	覆盖率
行覆盖率	69.1%
分支覆盖率	0.0%

模块	行覆盖率
crates.sandbox-core.src.daemon	██████████░░░░░░░░░░ 51.6%
crates.sandbox-core.src.instance	███████████████████░ 99.1%
crates.sandbox-core.src.process	█████████████░░░░░░░ 65.7%
crates.sandbox-core.src.capture	████████████████████ 100.0%
crates.sandbox-core.src.sandbox	███████████████████░ 98.8%
crates.sandbox-core.src.server	█████████████████░░░ 87.5%
crates.sandbox-core.src	███████████░░░░░░░░░ 55.3%
crates.sandbox-core.src.automation	███████████░░░░░░░░░ 58.8%

详细报告见 Rust 覆盖率 artifact

前端测试覆盖率

指标	覆盖率
行覆盖率	██░░░░░░░░░░░░░░░░░░ 11.4%
分支覆盖率	0.0%
函数覆盖率	17.6%
语句覆盖率	9.1%

文件	行覆盖率
src/renderer/api.ts	██░░░░░░░░░░░░░░░░░░ 11.4%

详细报告见前端覆盖率 artifact

✅ 所有检查通过，可以合入

点击 Squash and merge 合并此PR