chore: update n8n to v1.114.3 and optimize template fetching

Updates:
- Updated n8n from 1.113.3 to 1.114.3
- Updated n8n-core from 1.112.1 to 1.113.1
- Updated n8n-workflow from 1.110.0 to 1.111.0
- Updated @n8n/n8n-nodes-langchain from 1.112.2 to 1.113.1
- Rebuilt node database with 536 nodes
- Updated template database (2647 → 2653, +6 new templates)
- Sanitized 24 templates to remove API tokens

Performance Improvements:
- Optimized template update to fetch only last 2 weeks
- Reduced update time from 10+ minutes to ~60 seconds
- Added getMostRecentTemplateDate() to TemplateRepository
- Modified TemplateFetcher to support date-based filtering
- Update mode now fetches templates since (most_recent - 14 days)

All tests passing (933 unit, 249 integration)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/templates/template-repository.ts

@@ -442,7 +442,19 @@ export class TemplateRepository {
     const rows = this.db.prepare('SELECT id FROM templates').all() as { id: number }[];
     return new Set(rows.map(r => r.id));
   }
-  
+
+  /**
+   * Get the most recent template creation date
+   * Used in update mode to fetch only newer templates
+   */
+  getMostRecentTemplateDate(): Date | null {
+    const result = this.db.prepare('SELECT MAX(created_at) as max_date FROM templates').get() as { max_date: string | null } | undefined;
+    if (!result || !result.max_date) {
+      return null;
+    }
+    return new Date(result.max_date);
+  }
+
   /**
    * Check if a template exists in the database
    */