feat(auth): build freighter wallet connect authentication page

[chibokaxavier]

Closes #26

Changes Made

• New Authentication Route: Built the /login page with dark/minimal UI styling consistent with the rest of the application.
• Freighter API Integration: Integrated @stellar/freighter-api to enable secure wallet connections and capture wallet addresses.
• Session Persistence: Configured localStorage checks combined with Freighter's session validation to maintain wallet connection states across page reloads and sessions.
• Error Handling: Implemented robust fallback logic to surface clear, user-friendly UI errors when connection requests fail, get rejected, or if the Freighter extension is missing.
• Global Auth Navigation Check: Updated the global <Navbar /> inside the main application to reflect the user's active connection state. When connected, the generic Login buttons are successfully replaced with a shortened display of the user's wallet address.
• ESLint Config: Added eslint.config.mjs to resolve compatibility issues with Next.js and ESLint v9.

Acceptance Criteria Met

• Connect/Disconnect button works as expected.
• Connected wallet address is displayed in shortened format (e.g., GABC...XYZ).
• Connection errors are surfaced with clear messages.
• Session state persists across reloads.
• npm run lint and npm run build succeed.
• Responsive design and aesthetic consistency preserved.
• No regression in existing chat, navigation, or wallet features.

How to Test

1. Pull the branch locally and run npm run dev.
2. Navigate to /login and click "Connect Freighter".
3. Verify that your wallet address is displayed correctly once the Freighter prompt is approved.
4. Try rejecting the prompt from Freighter to confirm the error message dynamically renders on the UI.
5. While connected, return to the Home page (/) to verify that the Navbar displays your active wallet connection rather than the generic action buttons.

[SudiptaPaul-31]

@chibokaxavier please resolve conflicts

[chibokaxavier]

Resolved Chief