0.3.8

Webmon 0.3.8: no clean-up loop near the memory limit

• Near the critical level, a full clean-up whose memory comes straight back
  (the game re-creates the native objects it freed) doubled the freeze rate
  instead of helping (log: 2 s stops every 2-3 s, 0.4 fps). The interval now
  doubles up to 40 s while memory rebounds; under 80 MB it stays at 5 s
• Three such clean-ups within a minute offer the fresh start: a session whose
  Lua data keeps growing (37 -> 310 MB in the log) can only recover that way
• Spread clean-ups take half of each frame (up to 60 ms) so they finish
  before memory climbs
• Bridge test: emergency, rebound backoff; README updated