Implement Catchup TV support and enhance program management - #200

This pull request adds comprehensive support for IPTV catchup/rewind features by tracking catchup capabilities on a per-channel basis and generating appropriate catchup stream URLs. It introduces new fields to the IptvChannel model, adapts program retention logic to each channel's catchup window, and implements robust parsing and URL generation for various catchup types.

Catchup/rewind feature support:

• Added new fields to IptvChannel (catchupDays, catchupType, catchupSource) to represent catchup capabilities, and updated parsing logic to populate these fields from both M3U and Xtream sources. [1] [2] [3] [4]
• Implemented the getCatchupUrl method to generate catchup stream URLs for different provider types (Xtream, Flussonic, TS, append/shift, and template-based) using the new channel fields.

Per-channel catchup window and program retention:

• Changed logic throughout the repository to calculate recent program cutoffs and retention limits per channel, based on each channel's catchup window, instead of using a fixed 30-minute window. This affects EPG parsing, now/next building, and recent program selection. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]

Xtream and M3U parsing improvements:

• Enhanced Xtream playlist parsing to extract catchup-related fields (tv_archive, tv_archive_duration) and set channel catchup properties accordingly. [1] [2]
• Improved credential extraction from Xtream URLs to handle cases where credentials are embedded in the URL path, not just query parameters.

Configuration and limits:

• Added a new constant to control the maximum number of recent catchup programs retained per channel.