security: add comprehensive secret/credential patterns to .gitignore

[nickotmazgin]

• Block environment files: .env, .env, .env.
• Block certificates: *.pem, *.key, *.crt, *.cer, *.der
• Block encrypted files: *.gpg, *.p12, *.pfx
• Block SSH keys: *_rsa, _dsa, _ecdsa, id_ed25519, id_rsa, id_dsa
• Block credentials: credentials*, secrets*, .npmrc, .pypirc

Description

Brief description of changes

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactoring

Testing

• Tested on GNOME Shell 44
• Tested on GNOME Shell 45
• Tested on GNOME Shell 46
• Tested on GNOME Shell 47
• No breaking changes

Screenshots (if applicable)

Add screenshots here.

Checklist

• My code follows the project's style guidelines
• I have self-reviewed my code
• I have commented my code where necessary
• I have updated the documentation accordingly
• My changes generate no new warnings
• I have added tests if applicable
• All new and existing tests pass

Additional Notes

Any additional information that reviewers should know.

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Note

Expand .gitignore to exclude environment files, certificates/keys, encrypted files, SSH keys, and common credentials configs.

• .gitignore:
  • Add ignore patterns for secrets/credentials:
    • Environment files: *.env, .env*, *.env.*
    • Certificates/keys: *.pem, *.key, *.crt, *.cer, *.der
    • Encrypted/PKCS files: *.gpg, *.p12, *.pfx
    • SSH keys: *_rsa, *_dsa, *_ecdsa, *id_ed25519*, id_rsa*, id_dsa*, id_ecdsa*
    • Credentials/config: credentials*, secrets*, .npmrc, .pypirc

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