fix(ci): use PACKAGE_NAME from workflow or debian/control (#46)

The generate-changelog.sh script had a hardcoded package name
"halpi2-daemon" instead of using the PACKAGE_NAME environment
variable from the workflow or reading it from debian/control.

This caused the generated debian/changelog to have a different
package name than debian/control, resulting in the error:
  dpkg-source: error: source package has two conflicting values

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude <noreply@anthropic.com>

Author: mairas

.github/scripts/generate-changelog.sh

@@ -31,8 +31,10 @@ if [ -z "$UPSTREAM" ] || [ -z "$REVISION" ]; then
     exit 1
 fi
 
-# Package name
-PACKAGE_NAME="halpi2-daemon"
+# Package name - use PACKAGE_NAME env var (from workflow) or read from debian/control
+if [ -z "${PACKAGE_NAME:-}" ]; then
+    PACKAGE_NAME=$(grep "^Source:" debian/control | cut -d: -f2 | tr -d ' ')
+fi
 
 # Debian version format: upstream-revision
 DEBIAN_VERSION="${UPSTREAM}-${REVISION}"