fix: resolve AI response format error and error handling issues

[petetan]

This PR fixes multiple issues that were causing the AI Release Tool to fail or report misleading success messages:

Issues Fixed

1. OpenAI API Error (400): Invalid response_format

• Problem: gpt-4o-mini model doesn't support response_format: 'json_object'
• Solution: Only use response_format for full GPT-4 models that support it
• Impact: AI analysis will now work with gpt-4o-mini and other compatible models

2. Git Commit Message Escaping

• Problem: Multi-line commit messages with quotes break shell commands
• Solution: Properly escape quotes and newlines in commit messages
• Impact: Release branch creation will succeed with complex commit messages

3. Misleading Success Reports

• Problem: Tool reports "✅ AI Release Tool completed successfully" even when errors occur
• Solution: ReleaseWorkflow now properly rethrows errors instead of returning default values
• Impact: Proper error reporting and failure detection

Testing

• All existing tests pass
• Build successful
• Addresses the specific error seen in GitHub Actions