Adds Supabase Signup integrations, date format and Zustand setup

[mano-ranjan]

🚀 Summary

This PR introduces core authentication and state management functionalities. It adds Supabase signup, user update, and logout flows. Also includes date formatting improvements for better readability and the initial setup for Zustand state management.

🧩 Related Issues / Tasks

In Progress #30

🛠️ Type of Change

• 🐞 Bug fix
• ✨ New feature
• 🧨 Breaking change
• 🔨 Enhancement/Refactor
• 📝 Documentation
• 📜 Other (please describe):

✅ Checklist

• The code is formatted with Prettier (npm run format or npx prettier --write .)
• PR references a linked Issue or Task number
• Tested on both iOS and Android devices/emulators
• No unnecessary logs or commented-out code
• UI changes, if any, have been reviewed visually
• All tests are passing (if applicable)
• Added or updated documentation where necessary

📸 Screenshots / Videos (UI changes only)

🧪 Test Plan

1. Verified Supabase authentication flows (signup, update, logout) using test accounts.
2. Checked date formatting across relevant screens.
3. Confirmed Zustand state updates reflect correctly in app state flow.