Nightly Release @ 20261017

Commit: 1ba579112c833e4dae08e8f2e3e1525e2be0f806
Message: Restore upstream CI packaging and remove fork-specific packaging layer

Align .github/build_github.sh, .github/workflows/build.yml and tests with
upstream LiveContainer/LiveContainer. The fork's package_ipas.py pipeline
downloaded a pinned sidestore-base-20260926.ipa from this repository's 1.0
release, which no longer exists, so every build failed with
"curl: (56) The requested URL returned error: 404".

Upstream builds fetch dylibify and the SideStore nightly IPA directly on every
run, so packaging no longer depends on any self-hosted release asset. Both
upstream download URLs were verified reachable.

Dropped fork-only files:

• .github/package_ipas.py
• .github/sidelc/PACKAGING.md
• tests/test_package_ipas.py

Retained the single update_json.py adaptation so generated AltStore sources
reference this fork instead of the upstream repository.

This is a nightly release created automatically with GitHub Actions workflow.