feat: implement multi-hop swap routing algorithm and UI components

[CyberXpert607]

Summary

Implements #73: Multi-Hop Optimal Route Finder for Token Swaps with automated pathfinding and price impact calculation.

Changes Made

1. Route Optimizer Service (lib/services/RouteOptimizer.ts)

• ✅ Builds liquidity pool graph
• ✅ Finds optimal multi-hop paths (e.g., USDC → WETH → WBTC)
• ✅ Calculates output amounts with fee adjustments
• ✅ Computes price impact and cumulative fees

2. Hook (lib/hooks/useRouteOptimizer.ts)

• ✅ Async route calculation (non-blocking UI)
• ✅ Web Worker support for heavy computation
• ✅ Main thread fallback for SSR/testing

3. UI Components

• ✅ SwapRouteDisplay — Shows path, fees, and price impact
• ✅ SwapCard — Complete swap interface with route integration

4. Dashboard Integration

• ✅ Added SwapCard to dashboard page

5. Testing

• ✅ Unit tests for RouteOptimizer (all passing)
• ✅ Component tests for SwapRouteDisplay

Related Issue

Closes #73

Checklist

• Multi-hop routing algorithm implemented
• Price impact and fee calculation
• Async execution (non-blocking UI)
• Swap UI displays route
• Tests passing
• Dashboard integration