Merge pull request #3 from grindlemire/improvements

Updated the gpr function with a much more detailed prompt to get better PR titles and descriptions from Claude. Also added several handy git and system utilities.

Changes to gpr:

Rewrote the Claude prompt with specific requirements for natural, conversational PR titles and descriptions
Added explicit instructions to avoid corporate-speak and AI-isms
Improved fallback handling when Claude fails
New utility functions:

gs() - shorter git status with branch info
glog() - pretty git log with graph and colors
gdiff() / gdiffs() - diff viewing with pager
psgrep() - search running processes
killport() - kill process on specific port (works on macOS and Linux)
extract() - universal archive extractor for tar, zip, etc.