Worker improvements:
- Add strongly-typed result structs for all job types
- Replace map[string]interface{} with specific result types
- Add JSON tags to JobResult for proper API serialization
- Fix processJob to handle different result types correctly
- Improve directory scan job with proper library folder resolution
- Add debug logging for scan operations
Media scanner improvements:
- Add nil checks for database in GetPollInterval and GetAutoScanEnabled
- Fix pdfcpu API call signature (add validateOnly parameter)
- Add debug logging for scanDirectory with file counters
- Improve error handling and reporting
Test fixes:
- Fix default poll interval expectation from 30s to 60s
- Add settingsCache initialization to scanner tests
- Add folders initialization to ProcessDirtyDirectories test