fix: resolve all build job failures

CI workflow (ci.yml):
- Proper YAML structure for all steps
- curl+tar checkout (act runners lack git)
- GITEATOKEN authentication for private repo access
- build-essential/gcc added to all jobs
- dpkg-buildpackage -d flag (skip apt dep check)

Build scripts:
- build-alpine.sh: Copy APKBUILD to /home/builduser before abuild
- build-arch.sh: Use REPO_DIR variable instead of $(pwd) in su commands

.gitea/workflows/ci.yml

@@ -116,6 +116,7 @@ jobs:
           sudo apt-get update
           sudo apt-get install -y build-essential debhelper pkg-config libsystemd-dev
       - name: Build Debian package
+        run: |
           sudo dpkg-buildpackage -us -uc -b -d
       - name: Upload to Gitea Release
         if: startsWith(github.ref, 'refs/tags/')