feat(agent): Implement Plan Mode - Verify Phase with content guidance

[ChaiWithJai]

Summary

Implement Verify Phase of the Plan/Act/Verify framework for Violet App Agent.

Details

After resources are created:

1. Verify all resources are accessible
2. Provide content guidance via Content Researcher subagent
3. Show upsell path for hosting options

Subagents Involved

• Content Researcher Subagent: Style guides and content briefs

Artifacts Produced

• Verification report
• Content style guide
• Next steps checklist

Expected UI Output

All resources verified

Your blog is ready at: http://daring-to-dream.localhost:5250

## What You'll Add

I've analyzed your style references...

**Style Guide: Daring To Dream**
Blending: Derek Sivers + Swyx + Ramit Sethi
...

Acceptance Criteria

• Resource verification checks all URLs
• Content Researcher generates style guide when style references present
• Upsell options displayed (FREE / STARTER / PRO / EXPORT)
• Clear next steps for user

Reference

• RFC-001: docs/RFC-001-plan-mode-ux.md
• Related: feat(agent): Implement Plan Mode - Plan Phase with capability separation #1720, feat(agent): Implement Plan Mode - Act Phase with real-time build progress #1721