[recommendation] Add FeeAlternatives component

[Tinna23]

Display the three fee tiers (economy / standard / fast) below the primary recommendation.

Layout:

• Three cards side by side
• Each card: tier label, fee value, confidence %, ledger target
• Color coding: economy=cyan, standard=green, fast=yellow
• Clicking a tier copies the fee to clipboard

Files to create:

• packages/ui/src/components/dashboard/FeeAlternatives.tsx

Files to touch:

• packages/ui/src/components/dashboard/RecommendationPanel.tsx — import and render FeeAlternatives