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/config/guides/research.md

@@ -0,0 +1,48 @@
+---
+name: Research
+description: Deep research — conduct background web research on a topic and append findings to the node.
+---
+
+# Research
+
+Conduct background research on the topic/person/concept and append findings to the node.
+
+## Steps
+
+1. **Read & Identify**
+   - Call `getNodesById` for the focused node
+   - Identify: what needs researching? (person's background, concept origins, recent developments, etc.)
+
+2. **Web Research**
+   - Call `webSearch` with targeted queries (1-2 searches)
+   - Focus on: background context, recent news, authoritative sources
+   - Extract the most relevant findings
+
+3. **Append Research**
+   Call `updateNode` ONCE using the `content` field with ONLY this section:
+
+   ```
+   ---
+   ## Research Notes
+
+   **Background:** [2-3 sentences of context]
+
+   **Key Findings:**
+   - [Finding 1]
+   - [Finding 2]
+   - [Finding 3]
+
+   **Sources:** [Brief attribution]
+   ```
+
+   Use `updates.content` (NOT chunk). Send ONLY the new section. The tool appends automatically.
+
+4. **Return Summary**
+   Reply with: "Researched [topic] — [key insight in <15 words]"
+
+## Rules
+
+- Keep total tool calls ≤ 5
+- Call `updateNode` exactly once
+- Focus on factual background, not opinion
+- Cite sources when possible