NEW YORK — In 2021, New York’s shelter system was under strain, with 61,000 residents. Officials said it was at capacity — or over. In 2023, the system is on track to house twice as many people. The population reached an eye-popping record 100,000 this week, thanks to familiar factors — the pandemic, skyrocketing rents — and acute ones: economic turmoil abroad and politicians in America seeking to thrust New York into a border crisis thousands of miles away. Sign up for The Morning newsletter fr