fix(rules): exclude weapon special ability dice from critical multiplication

PF1e (CRB Critical Hits): "additional damage dice from weapon special
abilities (such as flaming) are not multiplied when you score a critical
hit". _resolve_hit_damage now multiplies only the physical dice plus flat
bonuses by crit_mult; energy-typed component dice are added at 1x (the
energy share on the DR path and the per-component resistance step drop
their crit factor). Sneak precision dice were already excluded. README
and the module convention list updated.

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

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

tests/test_conformance_energy.py

@@ -125,6 +125,23 @@ def test_fire_immunity_negates_only_fire_component() -> None:
     assert eng._states[1].hp == 94
 
 
+def test_crit_does_not_multiply_flaming_dice() -> None:
+    """CRB Critical Hits: "additional damage dice from weapon special
+    abilities (such as flaming) are not multiplied when you score a critical
+    hit" — the slashing die rides the x2, the fire die stays at 1x."""
+    weapon = _attack("fiery-blade", _MIXED)
+    hero = _combatant("hero", attacks=(weapon,))
+    foe = _combatant("foe")
+    # d20=20 threatens, confirm 20 auto-crits, slashing 1d6=6, fire 1d6=4.
+    eng = _engine([hero, foe], [(0, 0), (0, 1)], ["players", "monsters"],
+                  [20, 20, 6, 4])
+    result = eng.resolve_attack(eng._states[0], eng._states[1], weapon)
+    assert result.crit is True
+    # 6x2 + 4 = 16 — NOT (6+4)x2 = 20 (the old multiply-everything convention).
+    assert result.damage == 16
+    assert eng._states[1].hp == 84
+
+
 def test_physical_only_weapon_ignores_energy_resistance() -> None:
     """(c) a physical-only weapon vs fire resistance is untouched."""
     weapon = _attack("sword", (("1d6", ("slashing",)),))