Animate a metronome that ticks a repeating two-tempo pattern in one self-contained HTML file

# Animate a metronome that ticks a repeating two-tempo pattern in one self-contained HTML file Make a small animated scene: a metronome. Write one file, `out/scene.html`, that works opened straight from disk with no network access. `spec.json` gives the page title, the stage size and the scene parameters. **Looks are not scored**: the page is opened in a headless browser (800x600 window, UTC time zone, network blocked) and checked by objective tests only. ## Scene contract - Draw the scene on one `<canvas>` or `<svg>` stage of `width` x `height` CSS pixels (spec.json), visible on load, with `<title>` containing spec.json `title`. - Animate continuously from load (`requestAnimationFrame` or timers); no click is needed unless stated below. - Expose `window.sceneState()`, returning the scene's current state in stage pixel coordinates (origin top-left of the stage): `{beats: <integer number of beats completed>, angle_deg: <arm angle, positive to the right>}`. Extra fields are fine. It must describe what is actually drawn. - Time 0 is `performance.now()` 0 (seconds = `performance.now()` / 1000). The tempo follows `pattern` in order: `beats` beats at the first `bpm`, then `beats` beats at the next, then the pattern repeats. A beat lasts 60 / bpm seconds, and the count starts at 0 before the first beat completes. The arm is at +`amplitude_deg` at time 0 and reaches the opposite side at each completed beat. `sceneState()` must return the state at the moment it is called. - The page must log no errors and throw no exceptions. Keep the file at most 200,000 bytes; no external scripts, fonts, images or URLs (inline everything). ## Checks (partial credit = share passed) 1. `self_contained`: `out/scene.html` exists, is at most 200,000 bytes, references no http(s) or protocol-relative URL, and requests nothing from the network when opened. 2. `has_canvas_or_svg`: a visible `<canvas>` or `<svg>` of at least 300x200 CSS pixels is on the page. 3. `frames_change`: over 3 s, some later screenshot differs from the first in at least 0.1% of pixels, and at least 3 of 30 screenshots differ. 4. `beat_count`: at every sample `sceneState().beats` equals the number of beats completed since time 0 under spec.json `pattern` (a 30 ms margin either side of a beat is allowed). 5. `arm_follows_beats`: at every sample `angle_deg` is within 4° of `amplitude_deg` × cos(π × b), where b is the fractional number of beats since time 0. 6. `no_console_errors`: no uncaught exception, `console.error` or browser error is logged during the run. ## How this run works - Work on your own: nobody will answer questions in this task, and writing to `ask/` counts against the run. - Write only under `out/`. Create `out/` if it is missing. Inputs are synthetic; don't fetch anything from the network. - Scoring is partial credit: each listed check is pass/fail, and the score is the share passed. Numbers are compared to within 0.005 unless the task says otherwise.