Task 559: Add E2E test for view mode toggle button

Status: DONE

Summary

Added E2E test verifying the view mode toggle button exists in the 3D orbital viewer

with correct aria-label and initial text.

Tests added (1 new)

• e2e/examples.spec.ts: "has view mode toggle button" — checks #view-mode-btn is attached,

has aria-label="視点切替", shows "慣性" text

Files changed

• ts/e2e/examples.spec.ts — 1 new E2E test (265→266 E2E total)

Impact

• Stats: 4,031 TS, 531 Rust, 266 E2E (4,828 total)