feat(studio): add persistent sandbox code projects

[evanlowe]

Summary

Add code projects backed by a personal persistent Studio Sandbox. Users can create named Python projects, reopen them in embedded VS Code, and recover their workspace from snapshots after a session expires. Projects share the existing workspace collection layout and include file counts, relative creation times, fullscreen editing, and Chinese/English UI text.

Studio owns the project templates and sends them to the image during initialization, so template changes do not require rebuilding the image. New projects initialize Git, a Python environment, and development guidance.

Deploy and both update paths create or reuse a missing persistent Sandbox Tool, defaulting to 8 CPUs / 16 GB and the regional 1.0.1 images for Volcengine Beijing, Shanghai, and BytePlus Singapore. Existing Tool bindings are preserved. An initial-startup fallback supports upgrades launched by older releases, and System Information exposes the workspace Tool ID.

Validation

• Production frontend and widget build
• Chinese/English resource checks and all 1,053 frontend tests
• Workspace, template, image-runtime, deployment and update tests; affected update assertions updated for the new Tool binding
• Pre-commit formatting, lint and secret scan
• Local Studio connected to a persistent Beijing Sandbox, including project initialization, template reload, metadata and session recovery checks

Regional image selection is covered by automated tests; Shanghai and BytePlus image pulls have not been verified live. Existing Tool configurations are not resized or replaced.