feat(studio): add unified agent workspace and deployment lifecycle

[evanlowe]

Summary

• add a unified Agent workspace with searchable Agent cards, editable drafts, version badges, evaluation datasets, read-only deployment settings, and update entry points
• add a React Flow based Agent build canvas with sequential, parallel, loop, and remote Agent composition
• connect create, debug, deploy, Runtime update, and Agent library flows while preserving session-scoped tool and Skill capabilities
• preserve unchanged Runtime edits without creating drafts, add explicit discard editing, and route new Agent creation through the creation-method chooser
• refine the sidebar to a compact responsive layout, remove the selected Runtime region badge, and add permission-gated Runtime deletion with confirmation and state cleanup
• replace deployment detail overflow with a focused five-stage progress card that highlights completed and active stages and hides unrelated details while deployment is running
• refresh the packaged Studio frontend assets and add regression coverage for the updated workflows

Verification

• npm test — 199 passed
• npm run build — passed
• uv run pytest tests/cli/test_studio_rbac.py tests/cli/test_frontend_runtime_proxy.py -q — 22 passed
• uv run --group dev --extra extensions --with greenlet pytest -n 16 — 898 passed, 2 skipped
• focused post-format Python regression suite — 111 passed
• manually verified sidebar sizing, selector behavior, permission-gated delete visibility, and Runtime update/deployment progress in the local Studio
• commit hooks: Ruff check, Ruff format, and hardcoded-secret detection passed