feat(navigation): add NavigationArrow component for within-floor room navigation

scenes/objects/NavigationArrow.tscn

@@ -0,0 +1,21 @@
+[gd_scene load_steps=2 format=3 uid="uid://cozypaw_navarrow"]
+
+[ext_resource type="Script" path="res://scripts/objects/navigation_arrow.gd" id="1_navarrow"]
+
+[node name="NavigationArrow" type="Node2D"]
+script = ExtResource("1_navarrow")
+
+[node name="Body" type="ColorRect" parent="."]
+color = Color(0.30, 0.60, 1.0, 0.85)
+size = Vector2(96, 96)
+position = Vector2(-48, -48)
+
+[node name="Label" type="Label" parent="."]
+offset_left = -24.0
+offset_top = -18.0
+offset_right = 24.0
+offset_bottom = 18.0
+text = "→"
+theme_override_font_sizes/font_size = 36
+horizontal_alignment = 1
+vertical_alignment = 1