feat: Create Groups Table Schema

[Olowodarey]

This PR introduces the database schema for groups, establishing the core structure needed to manage group data within the application.

Schema Fields

• id – Unique uuid identifier for the group, automatically generated
• name – Group name (text)
• owner_wallet – Wallet address of the group owner (text)
• created_at – Timestamp of group creation, defaults to current time in UTC

Security & Performance

• Enabled Row Level Security (RLS) policies for viewing, creating, updating, and deleting groups based on authentication and ownership
• Added indexes on owner_wallet and created_at for optimized queries

Verification

• Schema created successfully in database script
• All fields are properly defined and accessible
• Tested insert and query operations for groups (skipped per request)
• No errors during migration or runtime (skipped per request)

closes #53