Add conda env update command and file_bug_report Cursor command

[drbenvincent]

Summary

Adds developer experience improvements to the contributing documentation and Cursor commands.

Changes

• CONTRIBUTING.md: Add conda env update command for updating an existing environment from environment.yml (saves time vs delete/recreate cycle)
• .cursor/commands/file_bug_report.md: New Cursor command for filing bug reports via GitHub CLI with a structured workflow
• .gitignore: Add .github/issue_summaries/ for temporary issue files and update comment

Testing

• Manual verification of the conda env update command
• Cursor command follows established patterns from issue2pr.md

Checklist

• Pre-commit checks pass
• Documentation updated
• Follows project conventions

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📚 Documentation preview 📚: https://causalpy--644.org.readthedocs.build/en/644/

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.19%. Comparing base (df6f0ee) to head (c7dddb6).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #644   +/-   ##
=======================================
  Coverage   94.19%   94.19%           
=======================================
  Files          43       43           
  Lines        7316     7316           
  Branches      455      455           
=======================================
  Hits         6891     6891           
  Misses        262      262           
  Partials      163      163           

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