Improve Studio workspace controls and startup

[suhanpark]

Summary

Improve Studio responsiveness, controls, status reporting, and Modal workspace setup feedback without mixing in the Gaussian renderer implementation.

Why

The workspace initially blocked on configuration discovery, obscured remote deployment phases, and made several floating panels difficult to manage. These changes let the shell render immediately and move slow discovery into background requests while making active work easier to control.

Changes

• Render the workspace immediately while options load in the background
• Harden local and Modal startup and endpoint discovery
• Add clearer setup/deployment status and stop controls
• Improve draggable, resizable, collapsible workspace panels
• Improve dataset, hardware, remote-VM, results, and log interactions
• Expand API/runtime tests for the updated behavior

Validation

• python -m pytest tests/visualization/test_runtime.py -q (39 passed)
• pnpm build
• git diff --check

Stack

Depends on #1122. This draft targets studio/modal-remote-vm so the review contains only workspace hardening and controls. Retarget it as the lower PRs merge.