Remove rewards dashboard

[HHenry88]

Remove rewards-dashboard directory from apps
Remove rewards-dashboard from Makefile
Remove rewards-dashboard from env navbars

[coworker-bot]

XLabs/portal-bridge-ui #1288

Change Summary:

• Removal of "Rewards Dashboard" feature from the project's build workflow, navigation menus, and Makefile
• Deletion of entire apps/rewards-dashboard directory and associated configuration files
• Simplification of GitHub Actions workflow by removing rewards-related job and artifact download step

Risk Score: 3

• Explanation: Low-risk changes primarily involving feature removal and workflow cleanup. No critical system modifications detected.

Potential Vulnerabilities:

• None identified in this PR

Code Smell:
File: .github/workflows/build.yml:368-378

- name: Download Artifact
  uses: actions/download-artifact@v4
  with:
    name: build-rewards-dashboard
    path: rewards-dashboard

• Code: Unnecessary artifact download step that was not cleaned up
• Explanation: This block represents leftover code that no longer serves a purpose after removing the rewards dashboard, which could lead to confusion

Debug Log:

• None identified

Unintended Consequences:

• Potential impact on users expecting a rewards dashboard feature
• Navigation menus in multiple files (e.g., apps/connect/src/env/token-bridge.ts) now have a removed "Rewards" link which might cause user confusion if not updated elsewhere

Additional Observations:

• Clean and methodical removal of a feature across multiple project files
• Demonstrates good practice of removing unused code and simplifying project structure