Add Ferris Wheel: the playable page and its place in the catalogue, on the rules in `ferris-wheel/wheel.js` #177

A new game in the house style, mounted like the other forged games, built on the tested rules in ferris-wheel/wheel.js.

Done looks like:

• [ ] ferris-wheel/index.html draws the wheel, its gondolas and riders, the platform and the queue, and a balance needle under the hub, and drives it only through ferris-wheel/wheel.js; it adds no game rule of its own. Tap Board or Skip, or press B and S; the wheel steps on a steady beat. Ambient motion only in the fairground lights blinking. The HUD shows riders carried, steps left and the imbalance the rules report.
• [ ] Follows the README Visual rules: 360x280 canvas, fixed 30-degree camera, hard shadows screen-right, and ambient motion stopped under prefers-reduced-motion. Rider weights read by size as well as colour, and the balance needle shows the jam limit as a marked line. The canvas aria-label says how to play. The rules popup is at most four lines. There is a #mute button and no .mp3 is committed.
• [ ] Listed in GAMES in shell.js as { id: 'ferris-wheel', title: 'Ferris Wheel', blurb: 'Seat the queue without tipping the wheel', kind: 'Strategy', input: 'Tap', accent: '#b8475a', music: false, forged: true }. It has the matching <li> in the root index.html, a building in the town from town.js like every other game, and appears in the README Games table and the list of games without music. bun scripts/og.mjs has been run.
• [ ] rounds.mjs has a scripted round for ferris-wheel that reaches the end line. serve.test.mjs asserts that /ferris-wheel/ and /ferris-wheel/wheel.js answer 200. playtest.test.mjs passes for the folder, and bun test passes.

Files: ferris-wheel/index.html, shell.js, index.html, town.js if buildings are listed there, README.md, serve.test.mjs, rounds.mjs, og/. Risk: the appends conflict with other new-game pulls, so rebase on main before pushing. Fits: a builder.