fix(rules): let a natural 20 auto-succeed on escape

PF1e (SRD Combat Maneuvers): "Rolling a natural 20 while attempting a combat maneuver is always a success (except when attempting to escape from bonds)" - escaping a grapple is a combat maneuver, not bonds. _maneuver_escape now auto-succeeds on a natural 20 below CMD (the natural 1 auto-failure is unchanged). README updated.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/pf1e_simulator/combat.py

@@ -4384,7 +4384,11 @@ class CombatEngine:
         target_cmd = self._maneuver_cmd(target)
         roll = self._rng.d20()
         total = roll + escape_bonus
-        success = roll != 1 and total >= target_cmd
+        # PF1e (SRD Combat Maneuvers): "Rolling a natural 20 while attempting
+        # a combat maneuver is always a success (except when attempting to
+        # escape from bonds)" — escaping a grapple is a combat maneuver, not
+        # bonds, so the natural 20 auto-succeeds here too.
+        success = roll == _NATURAL_TWENTY or (roll != _NATURAL_ONE and total >= target_cmd)
         if success:
             target.active_conditions = [
                 ac for ac in target.active_conditions if ac.condition.name != "grappled"