ci: prepare deb repo artifact

[dumbmoron]

prepares a repo artifact for consumption by our hosting server

[greptile-apps]

Important Files Changed

Filename	Overview
.github/workflows/deb-repo.yml	New CI workflow that builds a reprepro Debian repository from the latest stable and prerelease GitHub releases, signs it with a GPG key, and uploads it as an artifact. One issue found: archive: false causes the artifact name parameter to be silently ignored, so the artifact will be named deb-repo.tar.gz instead of deb-repo.
package/helium-bin.spec	Adds Section: web to the Debian package metadata, consistent with the -S web section override already used in the deb-repo workflow's reprepro invocation.

_{Reviews (2): Last reviewed commit: "package: add section attribute for deb" | Re-trigger Greptile}

[dumbmoron]

@greptileai