chore(characters): regenerate every sidecar with the finger table

The finger roles only reach the runtime through <model>.rig.json, so a
character whose sidecar predates them keeps flat, open hands however good
the pose layer is. Aria, Momo, Miku and the Mannequin re-imported; all six
skins now carry 10 finger chains.

Verified on the Mannequin, which is untextured and so the clearest
diagnostic of the three checked: stock at the shoulder, trigger hand on the
grip, support hand out on the handguard, both fists closed, arms not
crossing. Its arm is a full 0.524 m against Taila's 0.468 and it scales the
weapon independently — 0.231 m of hand separation against her 0.217 — with
the slide-back loop never firing on either.

Known remaining: the support hand's wrist roll leaves the hand hanging a
little under the handguard rather than wrapping it squarely. The grip
POSITION is right on every character; it is the roll about the barrel that
wants another pass.

Co-Authored-By: Claude Opus 5 <[email protected]>

assets/characters/skins/miku.rig.json

@@ -10,23 +10,75 @@
       "DEF-neck",
       "DEF-head"
     ],
-    "shoulder.R": "DEF-shoulder.R",
     "shoulder.L": "DEF-shoulder.L",
+    "shoulder.R": "DEF-shoulder.R",
     "upper_arm.L": "DEF-upper_arm.L",
     "upper_arm.R": "DEF-upper_arm.R",
     "forearm.L": "DEF-forearm.L",
     "forearm.R": "DEF-forearm.R",
-    "thigh.R": "DEF-thigh.R",
     "thigh.L": "DEF-thigh.L",
-    "foot.L": "DEF-foot.L",
+    "thigh.R": "DEF-thigh.R",
     "foot.R": "DEF-foot.R",
-    "shin.L": "DEF-shin.L",
+    "foot.L": "DEF-foot.L",
     "shin.R": "DEF-shin.R",
-    "hand.L": "DEF-hand.L",
+    "shin.L": "DEF-shin.L",
     "hand.R": "DEF-hand.R",
+    "hand.L": "DEF-hand.L",
     "toe.R": "DEF-toe.R",
     "toe.L": "DEF-toe.L"
   },
+  "fingers": {
+    "thumb.L": [
+      "DEF-thumb.01.L",
+      "DEF-thumb.02.L",
+      "DEF-thumb.03.L"
+    ],
+    "index.L": [
+      "DEF-f_index.01.L",
+      "DEF-f_index.02.L",
+      "DEF-f_index.03.L"
+    ],
+    "middle.L": [
+      "DEF-f_middle.01.L",
+      "DEF-f_middle.02.L",
+      "DEF-f_middle.03.L"
+    ],
+    "ring.L": [
+      "DEF-f_ring.01.L",
+      "DEF-f_ring.02.L",
+      "DEF-f_ring.03.L"
+    ],
+    "pinky.L": [
+      "DEF-f_pinky.01.L",
+      "DEF-f_pinky.02.L",
+      "DEF-f_pinky.03.L"
+    ],
+    "thumb.R": [
+      "DEF-thumb.01.R",
+      "DEF-thumb.02.R",
+      "DEF-thumb.03.R"
+    ],
+    "index.R": [
+      "DEF-f_index.01.R",
+      "DEF-f_index.02.R",
+      "DEF-f_index.03.R"
+    ],
+    "middle.R": [
+      "DEF-f_middle.01.R",
+      "DEF-f_middle.02.R",
+      "DEF-f_middle.03.R"
+    ],
+    "ring.R": [
+      "DEF-f_ring.01.R",
+      "DEF-f_ring.02.R",
+      "DEF-f_ring.03.R"
+    ],
+    "pinky.R": [
+      "DEF-f_pinky.01.R",
+      "DEF-f_pinky.02.R",
+      "DEF-f_pinky.03.R"
+    ]
+  },
   "chains": [],
   "twist": [],
   "colliders": [