Improve error handling and security in release task

[jvmvik]

Summary

• Add nil-check for version regex match with informative error message
• Use Shellwords.escape() to safely handle tag names in shell commands
• Fix PKG_CONFIG_PATH handling to properly escape paths with special characters

Changes

1. Error Handling: Added validation for version extraction from meson.build with a clear error message if the pattern is not found
2. Shell Injection Prevention: Wrapped tag variable with Shellwords.escape() in git commands to prevent injection attacks
3. Path Escaping: Fixed PKG_CONFIG_PATH to use Shellwords.escape() instead of manual quoting, handling paths with special characters properly

Test plan

• Verify release task runs successfully with normal version strings
• Verify error message appears if meson.build format is changed
• Verify shell commands work correctly with Shellwords escaping

🤖 Generated with Claude Code