[HIGH] Bump flatted to 3.4.4

[OskarEichler]

Summary

• update the existing flatted lockfile entry from 3.3.1 to 3.4.4
• remain within the existing compatible 3.x range
• keep the fix lockfile-only

Security impact

flatted 3.3.1 is affected by GHSA-25h7-pfq9-p65f, an unbounded-recursion denial of service during parse revival, and GHSA-rf6f-7fwh-wjgh, prototype pollution through parse. Version 3.4.4 includes both fixes.

Test Plan

• yarn install --frozen-lockfile --ignore-scripts
• yarn why flatted confirmed 3.4.4
• yarn audit no longer reports flatted advisories
• yarn build
• yarn lint
• circular-reference stringify/parse compatibility check
• git diff --check

Changelog:

[INTERNAL] [SECURITY] - Bump flatted to 3.4.4.