Add support for more social links + edit existing README feature

[M-AhmedSajid]

Currently, GPRM allows adding a limited set of social links and generating a profile README, but there are two limitations:

• Missing modern platforms like Threads
• No ability to edit an already generated profile README

These limitations reduce flexibility for users who want to keep their profiles up-to-date or reflect newer platforms.

Feature Requests

1. Add More Social Links
   Support additional platforms such as:
   Threads
   (Optional: allow custom links for unsupported platforms)

Why this matters:
Developers are increasingly using newer platforms, and limiting options makes profiles feel outdated.

2. Edit Existing Profile README
   Allow users to:
   Load their existing README
   Modify sections (bio, stats, social links, etc.)
   Regenerate or update without starting from scratch

Why this matters:
Right now, users must recreate everything to make small changes, which is inefficient and discouraging.

Suggested Implementation

• Add a “Custom Link” option for flexibility
• Provide an “Import README” or “Edit Existing” button
• Parse existing README content into editable fields

Additional Context
These features would significantly improve usability and make GPRM more practical for long-term use.