feat(rotation): implement rotation utilities and enhance angle input handling

src/js/utils/rotation-utils.ts

@@ -0,0 +1,17 @@
+export const ROTATION_MIN = -360;
+export const ROTATION_MAX = 360;
+export const ROTATION_STEP = 0.1;
+
+export function clampRotation(value: number): number {
+  return Math.max(ROTATION_MIN, Math.min(ROTATION_MAX, value));
+}
+
+export function roundToStep(value: number): number {
+  return Math.round(value * 10) / 10;
+}
+
+export function parseAngleInput(raw: string, fallback = 0): number {
+  const parsed = parseFloat(raw);
+  if (!Number.isFinite(parsed)) return fallback;
+  return clampRotation(roundToStep(parsed));
+}