Create Watchlist Creation Modal

# 🧠 Concept
Simplify adding new monitoring targets.

## ⚠️ Problem
Users need a streamlined onboarding experience.

## 📁 Implementation Scope
- apps/web/components/watchlists/

## ✅ Requirements
- Wallet input
- Contract input
- Validation

## 🎯 Acceptance Criteria
- [ ] Modal implemented
- [ ] Validation working
- [ ] Submission successful