test(v9): seeded monkey (nightly, MONKEY=1) -- random user-shaped sequences with exact replay

Composes N random steps per editor from a fixed seed -- keyboard
shortcuts, typing (incl. CJK), navigation, and a small set of plausible
asc_* actions -- checks liveness after each (fatal dialog, editor
loaded, main-thread responsiveness bounded to 15s, long-action counter
debounced over 8s so an in-flight CJK font fetch is not mistaken for a
leak), attributes every asc_onError to its step and fails only on
Critical ones, then proves the document still saves. On failure it
prints seed + doc + step list and the exact replay command. This is the
layer for state-combination defects (tonight's select-all -> series
settings, the user's edit-a-title dialog): first 150x3 run is clean.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: chaxus