feat: Add .env.example file and update Navbar for market navigation

- Introduce a new .env.example file for Nostr and API configuration, including settings for push notifications and market relays.
- Update Navbar.vue to include a new navigation item for the market, enhancing user access to market features.
- Extend localization support by adding market translations in English, Spanish, and French.

src/stores/market.ts

@@ -1,5 +1,5 @@
 import { defineStore } from 'pinia'
-import { ref, computed } from 'vue'
+import { ref, computed, readonly } from 'vue'
 import { config } from '@/lib/config'
 
 // Types