Improve package mirror resiliency in misc/build.func and misc/install.func by adding fallback and detection logic for Debian/Ubuntu and Alpine CDNs. Changes include:
- Detect distro (debian vs ubuntu) and use appropriate mirror lists and primary mirror (ftp.debian.org vs archive.ubuntu.com).
- Add retry loops that try a shuffled list of regional mirrors, test connectivity, update repo files, and attempt package installs/updates again.
- For Alpine (apk) installs and updates, try alternate mirrors on failure, write /etc/apk/repositories, and surface clearer warnings/errors if all mirrors fail.
- Update interactive prompts and informational messages to reference the correct mirror list (Ubuntu vs Debian) and generalize prompt wording.
- Improve exit handling so failures are reported and abort the process when necessary.
These changes make automated installs more robust against CDN sync issues and unreachable primary mirrors.
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