fix(upgrade): refresh outdated cache after upgrades

[MrSnakeDoc]

📝 Description

Fix a regression where keg upgrade -a successfully upgraded packages, but keg upgrade -ac continued reporting them as outdated.

The outdated Homebrew snapshot was cached for up to 24 hours and was not refreshed after upgrades. The cache is now refreshed once after all successful upgrades complete.

A regression test was added to verify that brew outdated --json=v2 is executed and the cache is persisted.

🔗 Related Issue(s)

• Fixes #
• Related to #

🔄 Type of Change

• 🐛 Bug fix (non-breaking change fixing an issue)
• ✨ New feature (non-breaking change adding functionality)
• 💥 Breaking change (fix or feature with breaking changes)
• 📚 Documentation update
• 🔧 Code refactoring
• ⚙️ CI/CD pipeline update

📋 Checklist

• My code follows the project's style guidelines
• I have updated the documentation accordingly
• I have added tests for my changes
• All new and existing tests pass
• My changes don't affect performance negatively
• I have tested this on different Linux distributions
• I have verified Homebrew integration works correctly

📸 Screenshots (if applicable)

Not applicable.

🔍 Additional Notes

This is a non-breaking corrective release. The outdated cache is
refreshed once after the upgrade operation completes, avoiding
stale upgrade status while keeping the normal check path cached.