Phase 13: localStorage favorites for loadouts

[elfensky]

Summary

Favorites utility + UI component for saving loadouts to localStorage. Default storage mechanism — works without auth.

Parent: #162

Design

• Key: hb_loadouts
• Entry shape: { hash, name, createdAt }
• Deduped by hash
• Collapsible favorites list below the builder
• Each favorite: name + date, Load button (→ ?b=<hash>), Delete button

Files

• CREATE src/shared/utils/loadoutFavorites.mjs — getFavorites(), saveFavorite(), removeFavorite()
• CREATE src/__tests__/unit/shared/utils/loadoutFavorites.test.mjs
• CREATE src/features/loadout/FavoritesList.jsx

Size: S