feat: add smart cache protection for active apps

[seunggabi]

Problem

User reported that cache cleanup was deleting login sessions and preferences from actively used applications.

Solution

Implement multi-layer cache protection:

1. Protect installed apps' caches (from /Applications)
2. Protect running apps' caches (via lsappinfo)
3. Protect recently used caches (within MAC_OPS_CACHE_RECENT_DAYS, default: 3 days)
4. Only clean orphan caches from uninstalled/inactive apps older than MAC_OPS_CACHE_MAX_AGE_DAYS (default: 7 days)

Changes

• Add MAC_OPS_CACHE_RECENT_DAYS environment variable (default: 3)
• Collect installed app bundle IDs from /Applications
• Collect running app bundle IDs via lsappinfo
• Skip cache cleanup for protected apps
• Update README with configuration documentation and protection policy

Impact

• Prevents accidental deletion of login sessions, preferences, and active app data
• Only cleans truly orphaned caches from removed applications