fix(pipeline): stand the character up before scaling; reach bones by role

Fixes the two root causes behind four of the seven reported breakages, and
rejects the source that cannot be fixed.

STAND UP FIRST. flatten_and_scale() now derives the up axis from the
skeleton and rotates the model upright before measuring anything. Aria and
Momo are correct: 1.75 m tall, 1.43 x 0.41 and 1.52 x 0.39 across, verified
by render.

The up vector is measured from the FEET to the HIPS, not from the hips to
the head. The head is not a reliable landmark — the spine walk ends on the
last non-cosmetic bone in the chain, which on a rig with a facial skeleton
can sit BELOW the hips. Momo's did, so the first cut of this fix stood her
neatly on her head: right size, right proportions, upside down. Feet cannot
be mistaken.

REACH BONES BY ROLE. SkinnedPlayerModel gained _role_bone(), and set_weapon
uses it. Four characters could not hold a gun because one hardcoded lookup
knew three spellings and their hands are called "Right wrist" and
"J_Bip_R_Hand" — both resolved perfectly in the sidecar the whole time.

HIKARI IS REJECTED. She now fails the gate: her feet and spine disagree
about which way is up, so the stand-up correction cannot resolve her
either, on top of zero-length cosmetic bones and a second armature that was
smuggling its own clips into the export. That is not a tuning problem, it
is a file that has been through two toolchains. De-registered and removed
rather than shipped broken — which is what the gate is for.

Six GLB skins remain, all passing. Smoke 0 failures, 11/11 movement tests.

Still open, recorded in the skill: kiyoko faces backwards, miku's grown
hair stretches under animation, the mannequin's rifle hold does not
convince, and taila's front skirt clipping.

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

characters/skinned_player_model.gd

@@ -922,7 +922,7 @@ func set_weapon(script_path: String) -> void:
 			_measure_weapon(w)
 	)
 
-	var hand_idx := _find_bone(["RightHand", "Hand_R", "hand.R"])
+	var hand_idx := _role_bone("hand.R", ["RightHand", "Hand_R", "hand.R"])
 	if hand_idx >= 0:
 		_weapon_attachment = BoneAttachment3D.new()
 		_weapon_attachment.name = "WeaponAttachment"
@@ -995,6 +995,27 @@ func _measure_weapon(w: Node3D) -> void:
 
 # ── Helpers ───────────────────────────────────────────────────────────────────
 
+## A bone by its resolved ROLE, falling back to name matching.
+##
+## tools/rig_map.py resolves every rig to roles and writes them to the sidecar so
+## that nothing downstream has to guess a bone name — but a hardcoded lookup here
+## meant four characters could not hold a gun. Their hands resolve perfectly as
+## "Right wrist" and "J_Bip_R_Hand"; none of them matches a spelling this file
+## knew, so set_weapon fell through to parenting the weapon to the model root at
+## a fixed chest offset, where it is not attached to the character at all.
+##
+## The fallback stays for a model with no sidecar. It must never be the first
+## thing tried.
+func _role_bone(role: String, fallbacks: Array) -> int:
+	var roles: Dictionary = _rig_info.get("roles", {})
+	var actual := String(roles.get(role, ""))
+	if actual != "" and skeleton:
+		var b := skeleton.find_bone(actual)
+		if b >= 0:
+			return b
+	return _find_bone(fallbacks)
+
+
 func _find_bone(name_parts: Array) -> int:
 	if not skeleton:
 		return -1