docs: Document workflow activation limitation across skills

Add critical limitation notice that workflow activation is not supported
via API or MCP and requires manual activation in n8n UI.

Changes:
- WORKFLOW_GUIDE.md: Added prominent warning in lifecycle section with
  deployment steps for users
- SKILL.md (workflow-patterns): Added inline warning in deployment checklist
- scheduled_tasks.md: Added activation reminder in deployment checklist
- VALIDATION_GUIDE.md: Added to best practices "Do" section

Context: During practical workflow deployment, discovered that the
n8n_update_partial_workflow operation with active:true setting does not
activate workflows. This is a critical limitation that users must understand
to successfully deploy workflows built via MCP.

Locations updated (4 files):
1. skills/n8n-mcp-tools-expert/WORKFLOW_GUIDE.md (primary)
2. skills/n8n-workflow-patterns/SKILL.md (deployment phase)
3. skills/n8n-workflow-patterns/scheduled_tasks.md (deployment checklist)
4. skills/n8n-mcp-tools-expert/VALIDATION_GUIDE.md (best practices)

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

Co-Authored-By: Claude <noreply@anthropic.com>
Conceived by Romuald Członkowski - https://www.aiadvisors.pl/en

skills/n8n-mcp-tools-expert/VALIDATION_GUIDE.md

@@ -302,6 +302,7 @@ Use **ai-friendly** profile to reduce false positives.
 - Iterate validation loop
 - Trust auto-sanitization for operator issues
 - Use minimal profile for quick checks
+- Complete workflow activation manually in n8n UI (API/MCP cannot activate workflows)
 
 ### ❌ Don't
 

skills/n8n-mcp-tools-expert/WORKFLOW_GUIDE.md

@@ -273,16 +273,27 @@ n8n_validate_workflow({
    → Verify changes
 
 5. ACTIVATE (when ready)
+   ⚠️ **IMPORTANT LIMITATION**: Workflow activation is NOT supported via API or MCP.
+   Users must activate workflows manually in the n8n UI.
+
+   The following operation will NOT activate the workflow:
    n8n_update_partial_workflow({id, operations: [{
      type: "updateSettings",
      settings: {active: true}
    }]})
 
+   **Manual activation required**: Navigate to workflow in n8n UI and toggle activation.
+
 6. MONITOR
    n8n_list_executions({workflowId: id})
    n8n_get_execution({id: execution_id})
 ```
 
+**Deployment Note**: After creating and validating workflows via MCP, inform users they must:
+1. Open the workflow in n8n UI (provide workflow ID)
+2. Review the workflow configuration
+3. Manually activate the workflow using the activation toggle
+
 ---
 
 ## Common Patterns from Telemetry

skills/n8n-workflow-patterns/SKILL.md

@@ -133,7 +133,7 @@ When building ANY workflow, follow this checklist:
 
 ### Deployment Phase
 - [ ] Review workflow settings (execution order, timeout, error handling)
-- [ ] Activate workflow
+- [ ] Activate workflow ⚠️ **Manual activation required in n8n UI** (API/MCP cannot activate)
 - [ ] Monitor first executions
 - [ ] Document workflow purpose and data flow
 

skills/n8n-workflow-patterns/scheduled_tasks.md

@@ -709,6 +709,7 @@ Use `search_templates({query: "schedule"})` to find more!
 - [ ] Document workflow purpose
 - [ ] Set up monitoring
 - [ ] Configure alerts
+- [ ] Activate workflow in n8n UI ⚠️ **Manual activation required** (API/MCP cannot activate)
 - [ ] Test in production (short interval first)
 - [ ] Monitor first few executions