fix: repair 4 failing tests and add exit-code checks for reservation CI (#176)

scripts/main.gd

@@ -349,7 +349,7 @@ func _on_startup_new_game() -> void:
 	sync_dock_option(chosen_anchor)
 	save_settings()
 	# Backup current save before destructive reset (issue #178)
-	var _gs: GameState = GameState.new()
+	var _gs = GameState.new()
 	var _bk: String = _gs.backup_save()
 	if not _bk.is_empty():
 		push_event_safe("Backup saved before reset: %s" % _bk.get_file())

scripts/worker_cap_logic.gd

@@ -0,0 +1,27 @@
+## Worker cap calculation logic — extracted from main.gd for testability.
+## This module has no dependencies on GameState or scene nodes, making it
+## suitable for headless unit testing.
+
+const Constants := preload("res://scripts/constants.gd")
+
+
+## Calculate the worker capacity based on builds and constants.
+## - Base cap from Constants.BASE_WORKER_CAP
+## - Hut bonus for each completed hut from Constants.WORKER_CAP_BONUSES
+static func calculate_worker_cap(builds: Array) -> int:
+	var cap: int = Constants.BASE_WORKER_CAP
+	for build in builds:
+		if bool(build.get("complete", false)):
+			var kind: String = str(build.get("kind", ""))
+			cap += int(Constants.WORKER_CAP_BONUSES.get(kind, 0))
+	return cap
+
+
+## Check if the colony can recruit another worker.
+## - If no workers exist yet, always allow recruitment.
+## - Otherwise, compare current count against calculated cap.
+static func can_recruit(builds: Array, workers: Array) -> bool:
+	if workers.size() == 0:
+		return true
+	var cap: int = calculate_worker_cap(builds)
+	return workers.size() < cap

tests/test_recruit_worker.gd

@@ -80,7 +80,7 @@ func test_recruit_adds_worker_to_state(main: Control) -> void:
 		{"name": "Jun", "task": {"kind": "", "data": {}}},
 	])
 	_assert(main.can_recruit_worker(), "precondition: can recruit")
-	var initial_count := main.state.workers.size()
+	var initial_count: int = main.state.workers.size()
 	main.recruit_worker()
 	_assert_eq(main.state.workers.size(), initial_count + 1, "recruit: state workers count increases by 1")