Add Conkers: the playable page and its place in the catalogue, on the rules in `conkers/match.js` #258

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

Done looks like:

• [x] conkers/index.html draws a school playground under a horse-chestnut tree, your conker and the rival's hanging on their strings, and a power meter that sweeps up and down. Tap the canvas, or press Space, to swing when the meter is where you want it. It drives the game only through conkers/match.js and adds no game rule of its own. The HUD shows what the rules state reports.
• [x] Follows the README Visual rules: 360x280 canvas, fixed 30-degree camera, hard shadows screen-right, and ambient motion stopped under prefers-reduced-motion. Your conker differs from the rival's by its knot and a chalk mark as well as colour, and the meter's sweet spot is marked by a notch, not only tint. 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.
• [x] Listed in GAMES in shell.js as { id: 'conkers', title: 'Conkers', blurb: 'Time your swing to crack every rival conker in the playground', kind: 'Sport', input: 'Tap', accent: '#8a4b22', 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.
• [x] rounds.mjs has a scripted round for conkers that reaches the end line. serve.test.mjs asserts that /conkers/ and /conkers/match.js answer 200. playtest.test.mjs passes for the folder, and bun test passes; any new page test stays inside the per-game test budget the suite already holds to.

Files: conkers/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.

Waits for the rules issue to land on main.

Reviewed pull #283 at its head: ticked conkers/index.html draws a school playground under a horse-chestnut tree, your conker and the rival's hanging on their strings, and a power meter that sweeps up and down. Tap the canvas, or press Space, to swing when the meter is where you want it. It drives the game only through conkers/match.js and adds no game rule of its own. The HUD shows what the rules state reports.; Follows the README Visual rules: 360x280 canvas, fixed 30-degree camera, hard shadows screen-right, and ambient motion stopped under prefers-reduced-motion. Your conker differs from the rival's by its knot and a chalk mark as well as colour, and the meter's sweet spot is marked by a notch, not only tint. 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: 'conkers', title: 'Conkers', blurb: 'Time your swing to crack every rival conker in the playground', kind: 'Sport', input: 'Tap', accent: '#8a4b22', 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 conkers that reaches the end line. serve.test.mjs asserts that /conkers/ and /conkers/match.js answer 200. playtest.test.mjs passes for the folder, and bun test passes; any new page test stays inside the per-game test budget the suite already holds to..