chore: bump version to 0.4.0

[Shadow-Azure]

Problem

v0.3.0 shipped without Linux artifacts — the build-linux job and Linux headless CLI support (#48) landed on main only after v0.3.0 was tagged. There is currently no released version carrying Linux binaries.

Solution

Bump the three manually-managed version files 0.3.0 → 0.4.0 so a new tag/release can be cut:

• Cargo.toml (workspace version, covers all three crates via inheritance)
• electron-app/package.json
• release.sh

packages/*/package.json versions are intentionally not bumped — release.yml rewrites them at publish time from the git tag (see release/release-pipeline.md § Version Management).

Test Plan

• grep confirms no other hardcoded 0.3.0 in source (only a historical plan doc, left as-is)
• CI Gate passes on this PR
• After merge: git tag v0.4.0 → git push origin v0.4.0 → gh release create v0.4.0 → release.yml produces macOS + Linux assets and publishes npm (cli-box-skill + platform pkgs, incl. first cli-box-linux-x64)

🤖 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
Playwright E2E	✅ success
统一测试 (test.sh)	✅ success
安全检查	✅ success
发布模拟验证	✅ success
升级流程测试	✅ success
cli-box-skill 单元测试	✅ success

Rust 测试覆盖率

指标	覆盖率
行覆盖率	67.3%
分支覆盖率	0.0%

模块	行覆盖率
crates.cli-box-core.src.process	███████████░░░░░░░░░ 57.7%
crates.cli-box-core.src	███████████░░░░░░░░░ 55.3%
crates.cli-box-core.src.capture	█████████████████░░░ 85.8%
crates.cli-box-core.src.instance	███████████████████░ 99.1%
crates.cli-box-core.src.automation	███████████░░░░░░░░░ 58.3%
crates.cli-box-core.src.sandbox	███████████████████░ 98.8%
crates.cli-box-core.src.daemon	██████████░░░░░░░░░░ 52.6%
crates.cli-box-core.src.server	█████████████████░░░ 87.7%

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	████████████████░░░░ 78.0%
分支覆盖率	70.4%
函数覆盖率	74.2%
语句覆盖率	77.5%

文件	行覆盖率
src/tests/mocks/websocket.ts	██████████████████░░ 88.0%
src/tests/mocks/xterm.ts	████████████████████ 100.0%
src/main/daemon-bridge.ts	████████░░░░░░░░░░░░ 40.0%
src/renderer/api.ts	██████████████░░░░░░ 68.2%
src/renderer/screenshotSync.ts	████████████████████ 100.0%
src/renderer/scrollback.ts	██████████████████░░ 88.9%
src/renderer/tabState.ts	████████████████████ 100.0%
src/renderer/terminalBuffer.ts	████████████████████ 100.0%

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