Makes local dev work on Windows: cross-env for the server dev port, pnpm --parallel to run server+web together (replacing the POSIX-only '&'), PowerShell setup docs, engines widened to Node >=20, and a Node 20 + 24 CI matrix. CI keeps a stable required 'Build & test' status via an aggregate gate job so the matrix rename doesn't drop the context the main ruleset requires. Co-authored-by: BadAtCaptchas <2359196+BadAtCaptchas@users.noreply.github.com> Co-authored-by: Jannis Braun <151788261+TheZwiss@users.noreply.github.com>