Contests bugfix drive

[KineticTactic]

#33

Done so far:

• Fixed wrong CF problem links (getCFProblemUrl regex)
• fixed contest creation validation error (fineTunedProblems + missing "test" enum)
• added dev bypass to status/rooms routes
• created test-contest-setup script
• added exit warnings (beforeunload + popstate) with hidden back button during active matches.

For creating contests locally,

pnpm seed                  # if you haven't already
pnpm clear-contests
pnpm test-contest-setup
pnpm dev