add: safeFloatParserを追加

packages/frontend/src/scripts/safe-parse.ts

@@ -0,0 +1,11 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and other misskey contributors
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+export function safeParseFloat(str: unknown): number | null {
+	if (typeof str !== 'string' || str === '') return null;
+	const num = parseFloat(str);
+	if (isNaN(num)) return null;
+	return num;
+}