fix: use fork release updater

[alvins82]

What changed

• checks CasaOS-Install latest-release version.json instead of IceWhale’s version service
• compares the remote bundle tag with /var/lib/casaos/fork-release
• routes dashboard and shell updates to the fork’s latest install.sh
• adds configurable fork update URLs with safe HTTPS fallbacks
• adds regression tests for manifests, version ordering, URL fallback, and command quoting

Why

The inherited updater fetched IceWhale’s installer and could replace the fork-patched CasaOS components. It also could not detect new fork bundle releases.

Validation

• Go 1.21 Linux updater tests pass
• route package compiles and tests pass
• shell syntax and ShellCheck error-level validation pass
• static linux/amd64, linux/arm64, and linux/arm/v7 binaries build successfully

Full clean-VM validation is in progress before release promotion.