feat: implement movement state machine, FPS camera rig, and test level builder scaffolding

movement/movement_state_machine.gd

@@ -62,7 +62,7 @@ func _physics_process(delta: float) -> void:
 		jump_buffer_time = maxf(jump_buffer_time - delta, 0.0)
 
 	# Update chain timer
-	if chain_timer > 0.0:
+	if chain_timer > 0.0 and on_ground:
 		chain_timer -= delta
 		if chain_timer <= 0.0:
 			chain_count = 0
@@ -115,14 +115,23 @@ func switch_to(new_state_name: String, data: Dictionary = {}) -> void:
 
 func register_chain_mechanic(_mechanic_name: String) -> void:
 	if chain_timer > 0.0 and chain_count > 0:
-		chain_count = mini(chain_count + 1, 10)
+		chain_count += 1
 	else:
 		chain_count = 1
-	chain_timer = params.chain_window
-	current_chain_bonus = minf(
-		float(chain_count) * params.chain_bonus_per_success,
-		params.chain_bonus_cap
-	)
+	
+	# Shrink the chain window as the chain gets longer to make it increasingly punishing
+	# Drops by 0.05 seconds per successful chain, down to a minimum of 0.4 seconds
+	var current_window = maxf(0.4, params.chain_window - (float(chain_count) * 0.05))
+	chain_timer = current_window
+	
+	var raw_bonus = float(chain_count) * params.chain_bonus_per_success
+	if raw_bonus <= params.chain_bonus_cap:
+		current_chain_bonus = raw_bonus
+	else:
+		# Soft cap: diminishing returns past the cap
+		var over_bonus = raw_bonus - params.chain_bonus_cap
+		current_chain_bonus = params.chain_bonus_cap + (over_bonus / (1.0 + over_bonus * 3.0))
+		
 	movement_event.emit("chain_updated", {
 		"count": chain_count,
 		"bonus": current_chain_bonus