perf(ship): share per-team accent material instead of allocating per ship

_apply_team_color() allocated a fresh StandardMaterial3D on every call, and
ran at least twice per ship (once from _ready at the default team, once from
the team setter when the game mode assigns the real team). Cache one
StandardMaterial3D per team in a static dict on Ship and reuse it across
every ship on that team.

Game/scripts/ship.gd

@@ -38,6 +38,26 @@ var team: int = 0:
 		team = value
 		_apply_team_color()
 
+# Shared per-team accent material, built once per team and reused by every
+# ship — avoids allocating a fresh StandardMaterial3D from both _ready and
+# the team setter (previously ran at least twice per ship).
+static var _team_materials: Dictionary = {}  # team:int -> StandardMaterial3D
+
+
+static func _get_team_material(team: int) -> StandardMaterial3D:
+	if _team_materials.has(team):
+		return _team_materials[team]
+	var color: Color = TEAM_COLORS.get(team, TEAM_COLORS[0])
+	var accent := StandardMaterial3D.new()
+	accent.albedo_color = color
+	accent.metallic = 0.3
+	accent.roughness = 0.5
+	accent.emission_enabled = true
+	accent.emission = color
+	accent.emission_energy_multiplier = 0.35
+	_team_materials[team] = accent
+	return accent
+
 var controller: ShipController
 var _current_action: ShipAction = ShipAction.new()
 var _boundary: ArenaBoundary
@@ -93,14 +113,7 @@ func _ready():
 func _apply_team_color() -> void:
 	if not is_inside_tree():
 		return
-	var color: Color = TEAM_COLORS.get(team, TEAM_COLORS[0])
-	var accent := StandardMaterial3D.new()
-	accent.albedo_color = color
-	accent.metallic = 0.3
-	accent.roughness = 0.5
-	accent.emission_enabled = true
-	accent.emission = color
-	accent.emission_energy_multiplier = 0.35
+	var accent := _get_team_material(team)
 	for mesh_name in ["Nose", "TailFin"]:
 		var mesh := get_node_or_null(mesh_name) as MeshInstance3D
 		if mesh:

TODO.md

@@ -25,7 +25,6 @@ Bugs found in an adversarial review. None are gameplay- or physics-affecting, so
 
 ## Performance
 
-- [ ] Shared per-team materials instead of `Ship._apply_team_color()` allocating a fresh `StandardMaterial3D` and assigning it as `material_override` (and running at least twice per ship — once from `_ready`, once from the `team` setter). Removes the allocation and lets same-team ships batch.
 - [ ] Merge the four non-tinted ship meshes (Hull/Canopy/EngineGlowL/R) into one — 6 draw calls per ship down to 3. Irrelevant at 1v1; 36 calls before VFX at 3v3.
 - [ ] Name collision layers in `project.godot` and assign them — nothing configures `collision_layer`/`collision_mask` today, so every body tests against every other.
 - [ ] Measure `nebula_dust.gdshader`'s per-fragment depth-texture sample across 500 large soft billboards before adding more particle work.