fix(studio): harden runtime and sandbox flows

[evanlowe]

Summary

• normalize Runtime descriptions before deployment and retry without the optional description when AgentKit rejects it
• keep temporary sandbox conversations active and retry configured Tool IDs across Beijing and Shanghai while preserving the matched region
• add a link-style create entry to an empty Agent directory and carry the selected region into creation
• refresh the bundled Studio assets

Validation

• npm test: 282 passed
• npm run build: passed
• targeted pytest: 54 passed
• pre-commit: passed, including secret scanning
• Ruff 0.11.12: passed on changed Python files
• live sandbox region fallback create/delete: passed

Existing baseline checks

• full pytest: 977 passed, 4 skipped, with one pending-state failure reproduced on origin/main
• Pyright reports 7 existing cli_frontend.py errors, identical on origin/main