Orbital Slalom 3D

Build a tiny browser game called "Orbital Slalom 3D".

Game spec
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A third-person 3D gravity-racer written against raw WebGL with no libraries: a hover ship skims the surface of a spinning low-poly asteroid on a great-circle course ring. Thrust, brake and steer with the arrow keys or WASD (mouse steering and click-to-thrust also work); holding Shift/K breaks grip so the ship drifts sideways, charging a boost that launches on release. Ten glowing slalom gates sit off the ring at alternating offsets: crossing one scores by how centred the line was, and unbroken clean runs stack a multiplier up to the difficulty cap; clipping a crystal spike or missing a gate resets it. Exceed orbital velocity and you lift off, where drifting buoys become hazards and gravity eventually drags you back to the rock. A chase camera, minimap, next-gate arrow, speedo/drift bars and a 3-2-1 countdown make up the HUD; three laps (two on easy, four on hard) ends in a results card with a perfection bonus. Difficulty from ?difficulty=easy|medium|hard scales gate width, obstacle density, spin rate, grip, top speed, laps and score multiplier, and on-screen touch pads appear under pointer:coarse.

Hard constraints — the game will be embedded in a sandboxed iframe on a static gallery site, and a headless browser will screenshot it:

1. Output exactly ONE self-contained HTML file. All CSS and JS inline. Zero external requests: no CDNs, no external fonts, images, or sounds, no fetch/XHR/WebSocket. Any sound must be synthesized with WebAudio.
2. The iframe sandbox is "allow-scripts allow-pointer-lock" (plus an autoplay permission). So: no localStorage, cookies, or indexedDB (opaque origin — access throws); no popups, window.open, or navigation; no access to the parent page; alert()/prompt()/confirm() are silently blocked.
3. The playfield must be visible within 800 ms of load — that is when the screenshot is taken. No dead white screen. If there is a start screen, make it visually rich.
4. Controls: keyboard AND mouse must both work, plus on-screen touch buttons for phones. Call preventDefault() on game keys (arrows, space) so the page never scrolls.
5. The view is 16:9 and must scale to fill the viewport with no overflow or scrollbars.
6. Show a visible score. If the genre has a losing state, show a game-over screen with a restart (button and a key). Idle/clicker games skip game over but still need clear numeric feedback.
7. If you track a score, report it to the arcade shell so the player's best is remembered between visits: on every score change, call parent.postMessage({ source: "ai-arcade", type: "score", score: <number> }, "*"). It is safe to call it no matter what the parent does with it.
8. Keep it tiny: aim for under 400 lines, 60 fps, no frameworks. That 400-line target does not apply to 3D games — true 3D (a camera and perspective-projected world) or pseudo-3D (projected road/track, depth-sorted sprites) — which need their own software renderer and typically land at 800–1400 lines. The rest of this constraint still binds every game: 60 fps, no frameworks, no external assets, and no padding to reach a length.
9. Difficulty: the arcade shell passes the player's chosen difficulty as a URL query parameter. Read it with new URLSearchParams(location.search).get("difficulty") — the value is "easy", "medium", or "hard" (missing or unknown means "medium"). Make the three levels meaningfully different — speed, lives, enemy pressure, reaction time, whatever fits the genre; clicker/idle games with no losing state use starting resources and upgrade cost curves instead. Show the active level in the HUD. Without the parameter the game must be fully playable at its default (medium) tuning.

Return only the complete HTML file, no commentary.