Add shareable earnings chart feature

[marcusljf]

Introduces a shareable earnings chart modal and API route, allowing users to copy or download a chart image of their earnings. Updates UI components for improved styling consistency and integrates the share modal into the program dashboard.

https://github.com/user-attachments/assets/60e5e95e-862c-4fef-a22d-57586d8f7080

Summary by CodeRabbit

• New Features

  • Added earnings sharing functionality allowing partners to share earnings charts with dynamic image generation.
  • New share modal with options to toggle background theme (light/dark), copy chart to clipboard, and download as PNG.

• Style

  • Updated card styling with refined border radius and color adjustments for visual consistency.

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