Pigeon Post page: `pigeon-post/index.html` on the landed `pigeon-post/loft.js` rules, listed in the catalogue and the town #267

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

Done looks like:

• [ ] pigeon-post/index.html draws the dovecote on its hill and the villages around it, the pigeons flying the shown route, and drives it only through pigeon-post/loft.js; it adds no game rule of its own. Tap a village to send a pigeon there. Ambient motion only in the loft's weather flag. The HUD shows round, route length and score as the rules state reports them.
• [ ] Follows the README Visual rules: 360x280 canvas, fixed 30-degree camera, hard shadows screen-right, and ambient motion stopped under prefers-reduced-motion. Each village differs by roof shape as well as colour, and the shown step is marked by an outline, not only a 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: 'pigeon-post', title: 'Pigeon Post', blurb: 'Watch the pigeons fly out, then send them to the same villages in order', kind: 'Memory', input: 'Tap', accent: '#8a7fa6', 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 pigeon-post that reaches the end line. serve.test.mjs asserts that /pigeon-post/ and /pigeon-post/loft.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: pigeon-post/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.

The rules are on main in 77b9861 (pigeon-post/loft.js): showing, tick and send drive the show and the send phase. Replaces #241 and #264, parked only because issues they once waited on were split or closed; the rules they need are on main.