Add gas giant resource system

GasCounter.gd

@@ -0,0 +1,16 @@
+extends NeonNumber
+
+# Banked gas companion to the ore counter. Keeping it as the same neon
+# numeral language makes both resources equally legible without implying gas
+# can pay for ore-only construction.
+const GAS_GLOW: Color = Color(0.85, 0.52, 1.0)
+const GAS_CORE: Color = Color(0.2, 0.04, 0.28)
+
+
+func _ready() -> void:
+	glow_color = GAS_GLOW
+	core_color = GAS_CORE
+
+
+func _process(_delta: float) -> void:
+	set_amount(GameState.gas)