- Set diffAlgorithm to 'legacy' for Monaco DiffEditor
- Add maxComputationTime of 10s to avoid UI freeze on huge files
This addresses the issue where sessions with large JSON files (50k-100k+ lines)
would cause the UI to freeze. The 'legacy' algorithm is faster than 'advanced'
for large files, similar to VSCode's workaround for the same issue.
See: https://github.com/microsoft/vscode/issues/184037
Replace split/unified and context controls with icon toggles, add a word-wrap toggle (default on), and move the toolbar into the tab header to free vertical space.
Use OpenCode v2 file APIs for browsing and Monaco DiffEditor for session snapshot diffs, with local baseline language metadata and optional CDN language loading.
