fix(queue-daemon): make base branch configurable via KUGETSU_BASE_BRANCH

- Add KUGETSU_BASE_BRANCH env var (default: origin/main)
- Update check_task_completion() to use configurable base branch
- Update create_worktree() to use configurable base branch

Closes #165

skills/kugetsu/scripts/kugetsu-config.sh

@@ -28,6 +28,7 @@ TASK_TIMEOUT_HOURS="${TASK_TIMEOUT_HOURS:-1}"
 
 NETWORK_RETRY_ATTEMPTS="${NETWORK_RETRY_ATTEMPTS:-3}"
 NETWORK_RETRY_DELAY_SECONDS="${NETWORK_RETRY_DELAY_SECONDS:-5}"
+KUGETSU_BASE_BRANCH="${KUGETSU_BASE_BRANCH:-origin/main}"
 
 # Load user config overrides (~/.kugetsu/config)
 if [ -f "$KUGETSU_DIR/config" ]; then