Add Apple Bobbing: the playable page and its place in the catalogue, on the rules in `apple-bobbing/tub.js` #360

Make the Apple Bobbing rules playable and listed, in the same shape as tide-crossing/ and bumper-cars/.

Done looks like:

• apple-bobbing/index.html draws a fete water tub with the seeded apples bobbing on the offsets offset(apple, tick) gives, advanced by step on a steady clock. Tap an apple or pick it with the arrow keys to aim, and tap again or press Space to dunk; R starts a fresh seed. The HUD shows score, apples caught, breaths and ticks left. It drives the game only through the export of tub.js and adds no game rule of its own. The HUD reads from the rules state, and every move, refusal and end line is announced through an aria-live region.
• Follows the README Visual rules: 360x280 canvas via engine.js, fixed 30-degree camera, hard shadows screen-right, ambient motion held still under prefers-reduced-motion. The aimed apple differs from the others by shape as well as colour (a ring round it), and an apple at the top of its bob is marked by more than colour. 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 with id apple-bobbing, title Apple Bobbing, kind Timing, input Tap, music: false and forged: true; the matching <li> in the root index.html; 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 apple-bobbing that reaches an end line, serve.test.mjs asserts /apple-bobbing/ and /apple-bobbing/tub.js answer 200, a apple-bobbing/page.test.mjs stays inside the per-game test budget the suite already holds to, playtest.test.mjs passes for the folder, and bun test passes. bun scripts/design-lint.ts passes.

Files: apple-bobbing/index.html, apple-bobbing/page.test.mjs, shell.js, index.html, README.md, rounds.mjs, serve.test.mjs, og/. Risk: shell.js, index.html, README.md and serve.test.mjs are shared with every other page pull; rebase before pushing. Fits: a builder.

Reviewed pull #365 at its head: ticked apple-bobbing/index.html draws a fete water tub with the seeded apples bobbing on the offsets offset(apple, tick) gives, advanced by step on a steady clock. Tap an apple or pick it with the arrow keys to aim, and tap again or press Space to dunk; R starts a fresh seed. The HUD shows score, apples caught, breaths and ticks left. It drives the game only through the export of tub.js and adds no game rule of its own. The HUD reads from the rules state, and every move, refusal and end line is announced through an aria-live region.; Follows the README Visual rules: 360x280 canvas via engine.js, fixed 30-degree camera, hard shadows screen-right, ambient motion held still under prefers-reduced-motion. The aimed apple differs from the others by shape as well as colour (a ring round it), and an apple at the top of its bob is marked by more than colour. 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 with id apple-bobbing, title Apple Bobbing, kind Timing, input Tap, music: false and forged: true; the matching <li> in the root index.html; 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 apple-bobbing that reaches an end line, serve.test.mjs asserts /apple-bobbing/ and /apple-bobbing/tub.js answer 200, a apple-bobbing/page.test.mjs stays inside the per-game test budget the suite already holds to, playtest.test.mjs passes for the folder, and bun test passes. bun scripts/design-lint.ts passes..