feat(rah-light): replace workflows with guides system

- Remove entire workflow system (API routes, services, tools, components)
- Add guides system from main ra-h repo (for external agent integration)
- Update pane types: 'workflows' → 'guides' throughout
- Update LeftToolbar to show guides icon instead of workflows
- Update SettingsModal with GuidesViewer tab
- Add GuidesPane for browsing guides in main UI
- Clean up prompts to remove workflow references
- Update tool registry to remove workflow tools
- Add gray-matter package for frontmatter parsing

Guides are essential for RA-H Light as they help external agents
(via MCP) understand the knowledge base context and usage patterns.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/components/panes/index.ts

@@ -1,5 +1,5 @@
 export { default as NodePane } from './NodePane';
-export { default as WorkflowsPane } from './WorkflowsPane';
+export { default as GuidesPane } from './GuidesPane';
 export { default as DimensionsPane } from './DimensionsPane';
 export { default as MapPane } from './MapPane';
 export { default as ViewsPane } from './ViewsPane';