docs: add AGENTS.md with local-preview + PR-to-main workflow

Guidance for AI assistants (and the README) on how to edit the site:
plain static files, preview via a local server, ship through a PR that
merges to main and auto-deploys to thefatdragon.bcgen.ie.

AGENTS.md

@@ -0,0 +1,79 @@
+# AGENTS.md — The Fat Dragon website
+
+This file tells any AI coding assistant how to work on this website. Read it before
+making changes.
+
+## What this is
+
+The live website for **The Fat Dragon** — a board-game café & arcade in Ashbourne,
+Co. Meath. It is a **plain static site**: hand-written HTML, CSS and JavaScript with
+**no build step and no dependencies**. The files in this repo are served to visitors
+*exactly as they are committed* — what you see locally is what goes live.
+
+The site is live at **https://thefatdragon.bcgen.ie**.
+
+## Repo map
+
+| Path | What it is |
+|------|------------|
+| `index.html` | Home page |
+| `arcade.html`, `board-games.html`, `events.html`, `find-us.html` | Top-level pages |
+| `book-now/` | Booking pages (`index.html`, `arcade.html`, `dnd.html`, `table-games.html`) |
+| `css/style.css` | All styling (single stylesheet) |
+| `js/main.js` | All page JavaScript (nav toggle, etc.) |
+| `assets/` | Images (`.webp` photos, logo) |
+| `.forgejo/` | **Deploy automation — do not touch** (see "Guardrails") |
+
+Links between pages are **absolute** (e.g. `/css/style.css`, `/book-now/`). That is why
+you must preview through a local web server, not by opening the `.html` file directly.
+
+## The workflow (follow this every time)
+
+### 1. Make changes on a branch
+Never edit `main` directly. Start from an up-to-date `main` and create a branch:
+
+```bash
+git checkout main && git pull
+git checkout -b describe-your-change      # e.g. update-opening-hours
+```
+
+### 2. Preview locally before shipping
+From the repo root, start a local server and open it in a browser:
+
+```bash
+python3 -m http.server 8000
+# then open http://localhost:8000
+```
+(No Python? `npx serve` or any static file server works — just serve the repo root.)
+
+Visually check every page you touched. **Do not ship a change you have not previewed.**
+
+### 3. Open a pull request into `main`
+When it looks right, commit, push the branch, and open a PR targeting `main`:
+
+```bash
+git add -A
+git commit -m "Update opening hours on Find Us page"
+git push -u origin describe-your-change
+```
+Then open the pull request (UI or API) with `main` as the base. Use PRs even though
+direct pushes are allowed — they keep a clean, reviewable history of every change.
+
+### 4. Merge to publish
+Merging the PR into `main` triggers automatic deployment. The live site at
+**https://thefatdragon.bcgen.ie** updates within about a minute. There is nothing
+else to run or deploy.
+
+## Guardrails
+
+- **Keep it dependency-free static HTML/CSS/JS.** No frameworks, bundlers, or build
+  tools — anything added to the repo is served raw.
+- **Never edit `.forgejo/`** or anything related to deployment/hosting. That is managed
+  separately; changing it can break publishing.
+- Keep new images in `assets/`, use `.webp` where possible, and keep them reasonably
+  small so pages load fast.
+- After editing, check that internal links and images still resolve (you'll catch this
+  in the local preview).
+- Match the existing style: the look uses the Playfair Display / Orbitron / Inter fonts
+  and the classes already defined in `css/style.css` — reuse them rather than inventing
+  new patterns.