feat(hero): more hero, frame and readme layouts

[Shironex]

What

More looks for the hero banner, the frames and the README snippet, so users have more options to choose from. The owner reviewed the proposal and kept every option. Every new option defaults to today's look, and bun run docs:gallery leaves every committed gallery file byte for byte as it was.

Comparison page, every option rendered from the Nightjar fixture and the demo TUI, with the config behind each tile:

Hero layouts (hero.layout)

• stack (default): today's banner, text left, one to three tilted windows.
• spotlight: one large straight window running off the right and bottom edges.
• split: one window turned in perspective towards the text.
• row: text centered on top, one to four windows side by side.
• mosaic: a tilted wall of up to four shots, repeated, fading out towards the text.
• centered: text first, one window rising from the bottom edge and leaning back.

hero.shots now takes as many ids as the layout shows (3, 1, 1, 4, 4, 1) and defaults to that many of the first shots. A longer list is an error that names the layout.

Frame styles (frame.style)

• browser: toolbar with back, forward, reload and an address bar showing the new frame.address ('{url}' by default; tokens {url}, {name}, {title}, {id}, {lang}). Refused in tty mode; in cdp mode {url} is refused because the page is not known when framing.
• windows: a Windows 11 title bar, title left, caption buttons right.
• terminal: a terminal tab with a monospace title; in tty mode the bar takes the terminal background and drops the line under it.

Backgrounds (frame.background, hero.background)

• { type: 'mesh', colors }: two to five colors, the base plus glows from the four corners.
• { type: 'dots', color, dot, spacing }: a subtle dot grid.
• { type: 'noise', from, to, angle, amount }: a gradient with film grain from a fixed seed (same bytes every run).

README layouts (showcase readme --layout)

• table (default): today's table.
• rows: image and title plus caption side by side, alternating, one small table per entry.
• featured: the first image full width, the rest as a table of --cols thumbnails.
• details: one collapsible <details> per image, the first open.
• list: every image full width with its caption.

Each went through gh api markdown (gfm) and was screenshotted with GitHub's Markdown styles: every tag and attribute survived. I left out a <picture> light/dark layout: a config captures one color scheme, so there is no second image set to pair.

Decision: all options are kept. main was merged in (the Observatory theme, the v1 lockfiles, checkout v7) and the full gate re-run on the merged tree: 279 library tests, 163 site tests, both typechecks and docs:build pass.

Checklist

• A changeset (minor) describing every new option.
• Gates on macOS (Apple Silicon): bun run typecheck, bun run test (23 files, 277 passed, 2 skipped: Windows only), bun run --cwd site test (156 pass), bun run docs:build. Nothing here touches paths, processes, the PTY or shims.
• New keys (hero.layout, frame.address, the three background forms) have JSDoc with @default, validation that lists the allowed values, tests for defaults and every rejected form; the reference drift test now keys form defaults by form type, since angle lives in two forms.
• Tests are deterministic (fixture app, temp dirs, no golden images: covered-area and pixel checks) and each failed once against broken code: placement per layout, Windows bar colors, the terminal bar edge, dots spacing, noise amount, the address from a path nav, rows alternation, the row shot limit, browser in tty mode, and a changed noise default for the site drift test.