Update xGRIB Alpha catalogue to 0.2.4.0

[pob220]

Follow-up to #1392 and the maintainer guidance there.

Updates the OpenCPN Alpha catalogue to xGRIB 0.2.4.0 and removes the superseded entries.

• Removes seven obsolete 0.2.0.0 metadata files
• Replaces the seven 0.2.3.1 entries with 0.2.4.0
• Catalogue targets: macOS arm64, Debian 12/13 x86_64, Flatpak 25.08 x86_64, Windows x86, and Ubuntu 22.04/24.04 x86_64
• All seven metadata files pass the OpenCPN XSD validation
• All linked Cloudsmith artifacts are version 0.2.4.0+526.48a05c4 and returned HTTP 200 without authentication
• Linux/Flatpak ARM64 artifacts are published for direct testing but intentionally not catalogued pending physical-device validation

Source tag: https://github.com/pob220/xgrib_pi/tree/v0.2.4.0