- Add JsonTreeViewer component with collapse/expand for nested objects and arrays
- Add rainbow colors by depth level using CSS color-mix() with syntax theme tokens
- Add virtualization support (@tanstack/react-virtual) for large JSON files (>200 nodes)
- Add JsonTreeView wrapper with Expand All / Collapse All toolbar
- Integrate into FilesView: tree/text toggle button, JSON file detection
- Integrate into ToolPart: auto-detect JSON tool outputs, render as tree
- Integrate into ToolOutputDialog: JSON tree view in expanded dialog
- Add jsonTreeUtils.ts: parse, flatten, path utilities
No new dependencies - uses existing @tanstack/react-virtual.
Colors derived from existing syntax.* theme tokens - works across all themes.
Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>
