The player must destroy enemy defence stations to earn artifacts, so
purely defensive play no longer fits. Also correct the push mechanic
to match REQ-DEF-PUSH/REQ-WAV-BOSS-ADVANCE: pushing advances the boss
countdown rather than applying a blanket strength multiplier, and
periodic boss waves are now called out explicitly. Drop the survival-
time framing from the overview since it's no longer the goal.
Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DyCu8vwChKMbLJQ3xosYEN
