v1.4.0

• challenge mode is now the gauntlet: insane multi-command chains graded on real output, freshly parameterized each run (never the same twice)
• daily challenge: date-seeded run everyone gets the same, one attempt, streak, copyable share code (cmdchamp daily)
• practice mode: drill any reached level (mastery % shown), hints on, no timer, doesn't touch your progress
• playground: safe sandbox REPL — type any command, see it run, Tab explains what you typed (cmdchamp play)
• epic finale: bosses-defeated roll + certified stamp on the ROOT victory
• bulletproof sweep: terminal resize/Ctrl-Z handling, paste-escape safety, tiny-terminal wrapping, atomic writes, concurrent-reset locking