feat(client): hair highlight swatch + manifest JSON for exports (#719, #720)

#719: Add display-only hair highlight swatch (Option B) — auto-derived
from primary tint, non-interactive (MOUSE_FILTER_IGNORE).

#720: Remove DirAccess.open() fallback scanning (breaks in PCK exports).
Fully populate manifest.json (11 body types, 14 hair, 4 heads, 4
eyebrows, 8 clothing). Add tooling/generate-character-manifest script
and make manifest target for regeneration.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/assets/characters/manifest.json

@@ -1,13 +1,75 @@
 {
-  "body_types": ["average_m", "average_f", "muscular_m", "muscular_f", "teen_m", "teen_f"],
-  "heads": [],
-  "hair": ["bob", "buns", "buzzed", "long", "ponytail", "bald"],
-  "facial_hair": ["beard", "moustache", "mutton_chops"],
-  "eyebrows": [],
+  "body_types": [
+    "average_f",
+    "average_m",
+    "child",
+    "heavy_f",
+    "heavy_m",
+    "muscular_f",
+    "muscular_m",
+    "teen_f",
+    "teen_m",
+    "thin_f",
+    "thin_m"
+  ],
+  "heads": [
+    "head_001",
+    "head_002",
+    "head_003",
+    "head_004"
+  ],
+  "hair": [
+    "bald",
+    "balding",
+    "bob",
+    "buns",
+    "buzzed",
+    "buzzed_female",
+    "dreads",
+    "long",
+    "long_dreads",
+    "mohawk",
+    "ponytail",
+    "ponytail_f",
+    "simple_parted",
+    "slick_back"
+  ],
+  "facial_hair": [
+    "beard",
+    "moustache",
+    "mutton_chops"
+  ],
+  "eyebrows": [
+    "female",
+    "regular",
+    "teen",
+    "thick"
+  ],
   "clothing": {
-    "peasant_tunic": {"slot": "torso"},
-    "peasant_pants": {"slot": "legs"},
-    "peasant_shoes": {"slot": "feet"}
+    "boots_work": {
+      "slot": "feet"
+    },
+    "coveralls_basic": {
+      "slot": "torso"
+    },
+    "jacket_utility": {
+      "slot": "torso"
+    },
+    "pants_cargo": {
+      "slot": "legs"
+    },
+    "peasant_pants": {
+      "slot": "legs"
+    },
+    "peasant_shoes": {
+      "slot": "feet"
+    },
+    "peasant_tunic": {
+      "slot": "torso"
+    },
+    "shirt_henley": {
+      "slot": "torso"
+    }
   },
   "accessories": []
 }