NEW YORK — Najibullah Zazi went from Pakistan to suburban Denver beauty shops in a hunt for the supplies and skill to make hydrogen peroxide bombs for al-Qaida, authorities charged in papers describing one of the most significant post-9/11 terror threats to the United States. The 12-page memorandum outlining the alleged conspiracy also used the repeated phrase "and others," evidence of a possible al-Qaida cell plotting a homemade bomb attack on U.S.