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>

tests/evals/scenarios/index.ts

@@ -2,7 +2,6 @@ import { scenario as simpleQuery } from './simple-query';
 import { scenario as searchEmbeddings } from './search-embeddings';
 import { scenario as createNode } from './create-node';
 import { scenario as hardModeQuery } from './hard-mode-query';
-import { scenario as workflowIntegrate } from './workflow-integrate';
 import { scenario as updateNode } from './update-node';
 import { scenario as createEdge } from './create-edge';
 import { scenario as queryDimensions } from './query-dimensions';
@@ -22,7 +21,6 @@ export const scenarios = [
   getDimension,
   dimensionLifecycle,
   hardModeQuery,
-  workflowIntegrate,
   youtubeExtract,
   websiteExtract,
   paperExtract,