Refactor: Extract magic numbers and hardcoded values to configuration

[mapitman]

Move hardcoded configuration values to AppConfig or constants classes:

Locations:

• Duration thresholds in DiscScanner.cs (20, 60, 30 minutes)
• Encoding parameters in EncoderService.cs (CRF 22, preset slow, bitrate 160k)
• Probe size "400M" in DiscRipper.cs

Suggestions:

• Create EncodingProfile classes for different quality settings
• Use TitleFilterSettings for duration thresholds
• Make configuration values externally configurable

Priority: Low - Reduces hardcoding, improves flexibility