fix(ci): handle grep exit code 1 when .env contains only comments (#43)

The _export_unset function was failing in CI because grep -v '^#'
returns exit code 1 when no lines match (file contains only comments).
With set -o errexit, this caused the script to exit immediately.

The CI workflow creates .env with just a comment line:
  # Environment file for GitHub Actions

When _export_unset tries to grep out comments, no lines match, and
grep exits with code 1, terminating the script.

Fix: Add || true to the grep command to ignore the no-match exit code.

Also removed debug statements from the previous commit.

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

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

Author: mairas

run

@@ -91,23 +91,14 @@ function build-deb {
 
   # Set up environment
   dev-env
-  echo "DEBUG: dev-env completed"
 
   # Check if changelog was already generated by CI (shared-workflows)
   # If debian/changelog exists and was modified in the last 5 minutes, skip regeneration
-  echo "DEBUG: Checking debian/changelog..."
-  echo "DEBUG: PWD=$(pwd)"
-  echo "DEBUG: ls -la debian/changelog: $(ls -la debian/changelog 2>&1 || echo 'file not found')"
-
   if [ -f "debian/changelog" ]; then
-    echo "DEBUG: debian/changelog exists, checking age..."
     # Use stat -c for Linux, stat -f for macOS, handle errors gracefully
     CHANGELOG_MTIME=$(stat -c %Y debian/changelog 2>/dev/null) || CHANGELOG_MTIME=$(stat -f %m debian/changelog 2>/dev/null) || CHANGELOG_MTIME=0
-    echo "DEBUG: CHANGELOG_MTIME=$CHANGELOG_MTIME"
     CURRENT_TIME=$(date +%s)
-    echo "DEBUG: CURRENT_TIME=$CURRENT_TIME"
     CHANGELOG_AGE=$((CURRENT_TIME - CHANGELOG_MTIME))
-    echo "DEBUG: CHANGELOG_AGE=$CHANGELOG_AGE"
     if [ "$CHANGELOG_AGE" -lt 300 ]; then
       echo "📋 Using existing debian/changelog (generated by CI)"
     else
@@ -122,11 +113,8 @@ function build-deb {
           --force-distribution \
           "Automated release $PACKAGE_VERSION. See GitHub for details."
     fi
-  else
-    echo "DEBUG: debian/changelog does not exist"
   fi
 
-  echo "DEBUG: About to run dpkg-buildpackage..."
   dpkg-buildpackage -us -uc -b
 
   echo "✅ Debian package built successfully"
@@ -427,7 +415,8 @@ function _export_unset {
 
   # Need to use a temp file to avoid a subshell
   local tmpfile=$(mktemp)
-  grep -v '^#' $file >$tmpfile
+  # Use || true to handle files with only comments (grep returns 1 when no matches)
+  grep -v '^#' "$file" >"$tmpfile" || true
 
   while read -r line; do
     if [[ ! "$line" =~ ^[[:space:]]*$ ]]; then