feat(rules): sunder deals real weapon damage vs object hardness/hp; broken weapons usable at -2 with restricted crits

SRD Sunder + CRB 'Smashing an Object' / 'Conditions - Broken': weapons
carry Table 7-12 object stats (AttackSpec.hardness/hit_points/enhancement,
defaults by weapon class); a successful sunder deals the attacker's actual
physical weapon damage minus the target weapon's hardness, subtracted from
its hp. At <= half hp the weapon gains the broken condition - still usable
at -2 attack/damage, crits only on a natural 20 at x2. At <= 0 it is
destroyed (weapon_destroyed, unusable). The old flat str_mod+2 / durability
10 / synthetic 'disarmed' condition is gone. Firearm misfire carve-out kept
(broken firearms stay unusable until Quick Clear - misfire escalation not
modeled, documented).

tests/test_weapon_selection.py

@@ -2,10 +2,12 @@
 
 ``attack`` and ``full_attack`` accept ``Action.weapon_id`` — the id of one of
 the attacker's weapons. With it the engine strikes with THAT weapon instead of
-the ``weapon_for`` auto-selection; a choice that is unknown, broken, stolen,
-or unable to strike the target (out of reach / no line of effect) is rejected
-with ``weapon_unavailable`` and no attack is made. Without it, the
-auto-selection and the full-attack mechanics are byte-identical to before.
+the ``weapon_for`` auto-selection; a choice that is unknown, destroyed,
+stolen, dropped, or unable to strike the target (out of reach / no line of
+effect) is rejected with ``weapon_unavailable`` and no attack is made (a
+BROKEN melee weapon stays selectable — CRB "Broken" makes it usable at -2).
+Without it, the auto-selection and the full-attack mechanics are
+byte-identical to before.
 """
 from __future__ import annotations
 
@@ -133,15 +135,31 @@ def test_full_attack_without_choice_still_swings_all_melee_weapons() -> None:
     assert "shortsword vs foe d20=10+2=12" in joined
 
 
-# ── (b) broken weapon → weapon_unavailable ───────────────────────────────────
+# ── (b) broken / destroyed weapon selection ──────────────────────────────────
 
 
-def test_attack_with_broken_weapon_is_rejected() -> None:
-    eng, hero, foe = _duel([])  # empty script: any roll would raise
+def test_attack_with_broken_weapon_is_usable() -> None:
+    # CRB "Broken": a broken weapon is still usable — at -2 on attack and
+    # damage. The explicit choice is accepted: d20 10 + 2 - 2 = 10 vs AC 10
+    # -> HIT for 3 - 2 = 1 damage.
+    eng, hero, foe = _duel([10, 3])
     hero.weapon_broken.add("hero-short")
     result = eng._execute(
         hero, Action(kind="attack", target_id="foe", weapon_id="hero-short")
     )
+    assert result == ActionResult(kind="attack", ok=True, reason="ok")
+    assert "shortsword vs foe d20=10+2=10 AC 10 -> HIT 1 damage" in eng._transcript[-1]
+    assert foe.hp == 99
+
+
+def test_attack_with_destroyed_weapon_is_rejected() -> None:
+    # A destroyed weapon (hp <= 0, CRB "Smashing an Object": "ruined") is
+    # unusable: the explicit choice is rejected, no roll consumed.
+    eng, hero, foe = _duel([])  # empty script: any roll would raise
+    hero.weapon_destroyed.add("hero-short")
+    result = eng._execute(
+        hero, Action(kind="attack", target_id="foe", weapon_id="hero-short")
+    )
     assert result == ActionResult(
         kind="attack", ok=False, reason="weapon_unavailable"
     )
@@ -149,9 +167,9 @@ def test_attack_with_broken_weapon_is_rejected() -> None:
     assert foe.hp == 100
 
 
-def test_full_attack_with_broken_weapon_is_rejected() -> None:
+def test_full_attack_with_destroyed_weapon_is_rejected() -> None:
     eng, hero, foe = _duel([])
-    hero.weapon_broken.add("hero-short")
+    hero.weapon_destroyed.add("hero-short")
     result = eng._execute(
         hero, Action(kind="full_attack", target_id="foe", weapon_id="hero-short")
     )