fix(rules): natural weapons get no BAB iteratives, secondary attacks at -5

PF1e (CRB "Natural Attacks"):
- Natural weapons (natural=true) get exactly one swing per full attack,
  regardless of BAB (no BAB iteratives for natural attacks).
- Secondary natural attacks (secondary=true) attack at BAB -5; the
  Multiattack feat reduces this to -2.
- Manifested in combat.py (_full_attack_weapon, _resolve_swing),
  models.py (AttackSpec.natural/secondary), 6 data JSONs, 4 new tests,
  and README documentation.

1461 passed, ruff clean, basedpyright 0 errors.

data/pcs/oni.json

@@ -1,126 +1,127 @@
 {
-  "name": "Oni Triumvir",
-  "level": 4,
-  "size": "Medium",
-  "abilities": {
-    "str_score": 12,
-    "dex_score": 14,
-    "con_score": 14,
-    "int_score": 12,
-    "wis_score": 18,
-    "cha_score": 16
-  },
-  "hp_max": 36,
-  "ac": {
-    "total": 19,
-    "touch": 18,
-    "flat_footed": 17
-  },
-  "bab": 4,
-  "initiative_mod": 2,
-  "speed_land_ft": 30,
-  "saves": {
-    "fort": 7,
-    "ref": 7,
-    "will": 9
-  },
-  "casting_ability": "wis",
-  "spell_slots": {
-    "1": 4,
-    "2": 3
-  },
-  "resources": {
-    "channel_energy": 6
-  },
-  "attacks": [
+ "name": "Oni Triumvir",
+ "level": 4,
+ "size": "Medium",
+ "abilities": {
+  "str_score": 12,
+  "dex_score": 14,
+  "con_score": 14,
+  "int_score": 12,
+  "wis_score": 18,
+  "cha_score": 16
+ },
+ "hp_max": 36,
+ "ac": {
+  "total": 19,
+  "touch": 18,
+  "flat_footed": 17
+ },
+ "bab": 4,
+ "initiative_mod": 2,
+ "speed_land_ft": 30,
+ "saves": {
+  "fort": 7,
+  "ref": 7,
+  "will": 9
+ },
+ "casting_ability": "wis",
+ "spell_slots": {
+  "1": 4,
+  "2": 3
+ },
+ "resources": {
+  "channel_energy": 6
+ },
+ "attacks": [
+  {
+   "name": "Longbow",
+   "kind": "ranged",
+   "attack_bonus": 6,
+   "damage": [
     {
-      "name": "Longbow",
-      "kind": "ranged",
-      "attack_bonus": 6,
-      "damage": [
-        {
-          "formula": "1d8",
-          "types": [
-            "piercing"
-          ]
-        }
-      ],
-      "damage_bonus": 0,
-      "crit_range": 20,
-      "crit_mult": 3,
-      "reach_ft": 5,
-      "count": 1,
-      "range_increment_ft": 100
-    },
-    {
-      "name": "Alchemist's Fire",
-      "kind": "touch",
-      "attack_bonus": 6,
-      "damage": [
-        {
-          "formula": "1d6",
-          "types": [
-            "fire"
-          ]
-        }
-      ],
-      "damage_bonus": 0,
-      "crit_range": 20,
-      "crit_mult": 2,
-      "reach_ft": 5,
-      "count": 1,
-      "range_increment_ft": 10
-    },
-    {
-      "name": "Attaques naturelles (Shifter Claws / formes fées)",
-      "kind": "melee",
-      "attack_bonus": 5,
-      "damage": [
-        {
-          "formula": "1d6",
-          "types": [
-            "slashing"
-          ]
-        }
-      ],
-      "damage_bonus": 1,
-      "crit_range": 20,
-      "crit_mult": 2,
-      "reach_ft": 5,
-      "count": 1
+     "formula": "1d8",
+     "types": [
+      "piercing"
+     ]
     }
-  ],
-  "source": "fiches_personnages/oni_sheet.json",
-  "notes": "Armes placeholder Foundry sans dégâts encodés omises : 'une Pioche' (non maîtrisée) et 'Weapon' (à remplacer par la vraie arme).",
-  "features": [
-    "Summon Good Monster",
-    "Sacred Summons",
-    "Selective Channeling",
-    "Extremely Fashionable",
-    "Exalted of the Society (Cleric, Pathfinder Society)",
-    "Bitter",
-    "Ambitious"
-  ],
-  "spells": [
-    "Guidance",
-    "Detect Magic",
-    "Stabilize",
-    "Read Magic",
-    "Detect Poison",
-    "Purify Food and Drink",
-    "Summon Monster I",
-    "Shield of Faith",
-    "Forbid Action",
-    "Cure Light Wounds",
-    "Hidden Diplomacy",
-    "Protection from Evil",
-    "Bless",
-    "Summon Monster II",
-    "Cure Moderate Wounds",
-    "Sound Burst",
-    "Suppress Charms and Compulsions",
-    "Delay Poison",
-    "Ironskin",
-    "Restoration, Lesser"
-  ]
+   ],
+   "damage_bonus": 0,
+   "crit_range": 20,
+   "crit_mult": 3,
+   "reach_ft": 5,
+   "count": 1,
+   "range_increment_ft": 100
+  },
+  {
+   "name": "Alchemist's Fire",
+   "kind": "touch",
+   "attack_bonus": 6,
+   "damage": [
+    {
+     "formula": "1d6",
+     "types": [
+      "fire"
+     ]
+    }
+   ],
+   "damage_bonus": 0,
+   "crit_range": 20,
+   "crit_mult": 2,
+   "reach_ft": 5,
+   "count": 1,
+   "range_increment_ft": 10
+  },
+  {
+   "name": "Attaques naturelles (Shifter Claws / formes fées)",
+   "kind": "melee",
+   "attack_bonus": 5,
+   "damage": [
+    {
+     "formula": "1d6",
+     "types": [
+      "slashing"
+     ]
+    }
+   ],
+   "damage_bonus": 1,
+   "crit_range": 20,
+   "crit_mult": 2,
+   "reach_ft": 5,
+   "count": 1,
+   "natural": true
+  }
+ ],
+ "source": "fiches_personnages/oni_sheet.json",
+ "notes": "Armes placeholder Foundry sans dégâts encodés omises : 'une Pioche' (non maîtrisée) et 'Weapon' (à remplacer par la vraie arme).",
+ "features": [
+  "Summon Good Monster",
+  "Sacred Summons",
+  "Selective Channeling",
+  "Extremely Fashionable",
+  "Exalted of the Society (Cleric, Pathfinder Society)",
+  "Bitter",
+  "Ambitious"
+ ],
+ "spells": [
+  "Guidance",
+  "Detect Magic",
+  "Stabilize",
+  "Read Magic",
+  "Detect Poison",
+  "Purify Food and Drink",
+  "Summon Monster I",
+  "Shield of Faith",
+  "Forbid Action",
+  "Cure Light Wounds",
+  "Hidden Diplomacy",
+  "Protection from Evil",
+  "Bless",
+  "Summon Monster II",
+  "Cure Moderate Wounds",
+  "Sound Burst",
+  "Suppress Charms and Compulsions",
+  "Delay Poison",
+  "Ironskin",
+  "Restoration, Lesser"
+ ]
 }