Of course this is a lie. The funny thing is that she didn't need to lie. There are no residency requirements for Congress in the state of Massachusetts.
If she isn't running against Clark, who could she possibly run against? There are only 3 other districts near her and the city of Boston.
7th District Mike Capuano - This is northern part of the Boston and some suburbs. He's really liberal and part of the Progressive Caucus. He's also been in office since 1999 and incredibly popular in the district. No one even bothered to run against him this year.
4th District Joseph Kennedy - I know Wu is dumb but she couldn't be dumb enough to think she could beat a Kennedy in the State of Massachusetts, right? He received 98.6% of the vote in last election primary. Also the people of South Boston don't seem to be the demographic Wu is going to cater to.
6th District Seth Moulton - One of the rising stars of the Democratic Party. If Wu is going to run on tech, good luck running against a guy with a Physics degree from Harvard. He's also a Marine with four tours in Iraq under his belt. Imagine Wu complaining about people calling her names on Twitter next to this guy:
Anyways, Wu has no intention of running for anything . She is just milking this for some attention now that her game turned out to be a giant failure and not even the garbage clickbait sites will pay her for "journalism". In a year when deadlines start approaching we'll get a "I decided not to run because of death threats and fear for my safety" diatribe. Congress is the big leagues and a lazy, unemployed college flunky would get smashed by established candidates with powerful people backing them.
One possible funny scenario is if Wu chooses to use this scam to get more money, she would be on the hook with the FEC. So if she mentions this in a Patreon, Kickstarter, or just solicits donations for a campaign, it counts as raising funds she has to register with the FEC. I believe the threshold is $5,000 and that becomes public record. It would be funny if her dumb farce cost Frank a bunch of money having to file some meaningless FEC paperwork for a race she doesn't even run in.