docs: add AGENTS.md and CLAUDE.md for coding agents

AGENTS.md

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+# AGENTS.md
+
+Guidance for coding agents working on the Ghost Assembly organisation site,
+<https://ghost-assembly.github.io/>. Read `README.md` for the human overview; this file
+holds the rules that are not obvious from the code.
+
+## What gets published
+
+- GitHub Pages deploys from branch `main`, folder `/docs` (build type "legacy", not an
+  Actions workflow). Merging to `main` publishes.
+- **Everything in `docs/` is public, and nothing outside it is.** Keep tooling, tests,
+  the design notes and the source logo out of `docs/`.
+- `docs/.nojekyll` disables Jekyll. Do not remove it.
+- The project docs at `/quickrem/`, `/quicktiler/` and `/quickts/` are published from
+  those projects' own repositories. Never create `docs/quickrem/` (or any other project
+  name) here — it would collide with them.
+
+## Hard constraints
+
+These are deliberate and the test suite enforces most of them.
+
+- Hand-written HTML and CSS, no framework, no build step, no bundler.
+- No JavaScript on the page. Theme follows `prefers-color-scheme`; navigation is anchors.
+- No third-party requests from the page. Fonts and images are self-hosted in
+  `docs/assets/`. A test fails on any request to another origin.
+- WCAG 2.2 AA. axe runs in both colour schemes with the `wcag2a`, `wcag2aa`,
+  `wcag21aa`, `wcag22aa` and `best-practice` tags, and must report zero violations.
+- No horizontal scroll at 360px wide.
+- Motion only inside `@media (prefers-reduced-motion: no-preference)`. The hero halo is
+  the page's one animation; a test checks it runs normally and never under reduced
+  motion.
+
+## Design rules
+
+- Colour tokens live on `:root` in `docs/style.css`, with a light override under
+  `prefers-color-scheme: light`. Brand stops are sampled from the logo: cyan `#00a8fc`,
+  blue `#2f5afc`, magenta `#d601fc`; paper `#03030a`.
+- `.night` (top bar and hero) re-declares the dark tokens so it stays dark in both
+  schemes — the logo's silver wordmark is illegible on a light background. Keep it that
+  way.
+- The gradient is decoration only (halo, button border, project rules). Never put text
+  on it.
+- Headings use Orbitron (self-hosted, OFL); body text uses the system font stack.
+- Use logical properties (`margin-block-start`, `padding-inline-start`), not physical
+  ones.
+
+## Commands
+
+The toolchain is pinned in `mise.toml`; commands live in the `justfile`.
+
+```bash
+just setup    # mise install, npm ci, Playwright's Chromium and Firefox
+just run      # serve docs/ on http://localhost:8000
+just test     # Playwright suite (Chromium and Firefox)
+just lint     # prettier --check, actionlint, zizmor
+just fmt      # prettier --write
+just ci       # lint, test, security, build — exactly what CI runs
+just assets   # regenerate docs/assets images and assets/avatar.png
+```
+
+Run `just ci` before claiming a change works. Tests target Chromium and Firefox only;
+WebKit is not supported on the maintainer's Fedora base, so do not add it.
+
+## Adding or changing a project
+
+A project appears in three places, and all three must change together:
+
+1. `docs/index.html` — an `<article class="project">` in the right group. Link Docs to
+   `https://ghost-assembly.github.io/<slug>/` only if that project publishes a docs
+   site; otherwise give it Source only.
+2. `tests/site.spec.js` — the `projects` list at the top, so its links are checked.
+3. The org profile README, `profile/README.md` in the separate
+   [Ghost-Assembly/.github](https://github.com/Ghost-Assembly/.github) repository.
+
+Take summaries from the project's own `README.md` and, for GNOME extensions, the
+supported versions from `shell-version` in its `metadata.json`. Do not invent claims.
+
+## Images
+
+Every image in `docs/assets/` is derived from `assets/logo-source.png` by
+`just assets`. Edit the recipe rather than individual images. The crop offsets in the
+recipe are the measured bounds of the emblem and the whole logo in the 1254px source.
+`assets/avatar.png` is the GitHub org avatar and is intentionally not published.
+
+## Change workflow
+
+- Branch from `main`, open a pull request, and squash-merge once the `ci` job (which
+  runs `just ci`) passes.
+- Conventional Commits, imperative subject, no trailing period.
+- Third-party GitHub Actions are pinned by commit SHA with the version in a comment.
+- `design/` holds the agreed design notes. Update them when the design changes.

CLAUDE.md

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+@AGENTS.md