- New Action kind activate_power_attack: free action that sets
state.power_attack = True when the combatant has the Power Attack feat;
logged no-op otherwise. Routed via _execute_movement (free-action branch)
to keep _execute under the C901 complexity ceiling.
- Consume deed_up_close_and_deadly in resolve_attack: the first attack
resolved while the flag is set gains +1d6 if it is a ranged attack within
30 ft; the flag is reset in all cases (benefit lost if out of range or
not ranged). Extracted into _consume_up_close_and_deadly helper.
- Document activate_power_attack, corrected deed semantics, and the
power_attack snapshot key in README.
- Add tests/test_engine_fixes.py (5 tests): PA activation, no-feat no-op,
deed+ranged within 30ft, deed out-of-range, deed melee.
ctan