Add Hedge Maze: the playable page and its place in the catalogue, on the rules in `hedge-maze/maze.js` #151

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

Done looks like:

• [ ] hedge-maze/index.html draws the hedges, the path, the walker and the fountain, and drives it only through hedge-maze/maze.js; it adds no game rule of its own. Swipe or tap beside the walker to step that way, or use the arrow keys. Ambient motion only in the fountain splashing. 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. The walker and the fountain stand out from the hedges by shape as well as 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 as { id: 'hedge-maze', title: 'Hedge Maze', blurb: 'Find the way through the hedges to the fountain before the gardener rings the bell', kind: 'Puzzle', input: 'Keys', accent: '#3d6e4f', 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 hedge-maze that reaches the end line. serve.test.mjs asserts that /hedge-maze/ and /hedge-maze/maze.js answer 200. playtest.test.mjs passes for the folder, and bun test passes.

Files: hedge-maze/index.html, shell.js, index.html, 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.