Consolidate gateway-gamers sites, dedupe shared header/footer/images

Merge the four independent gateway-gamers.net site repos (40k-rankings,
aos-rankings, kingmaker, scouting) into one monorepo under sites/,
preserving each site's full commit history via a manual subtree-style
merge (git-subtree isn't available in this environment).

- shared/: header.template.html (nav swapped in per site), footer.html,
  and images/ — previously byte-identical copies duplicated 4x (~100MB).
- Each site's public/footer.html and public/images are now symlinks into
  shared/; public/header.html is generated at predev/prebuild time from
  shared/header.template.html + the site's own nav.html, so nav bars stay
  individual while everything else about the header is shared.
- Single root .gitlab-ci.yml with path-scoped build/deploy jobs per site
  plus a deploy:shared job, replacing the 4 separate per-repo pipelines.
- nginx confs (kept per-site as reference, same as before) gain
  location /images/ and location = /footer.html alias blocks pointing at
  a shared webserver directory, so the deployed site no longer duplicates
  the images either — see README.md for the full layout and the runbook
  for applying this on the webserver.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SBzcNkW7JcYipnAX6HfgmK

README.md

@@ -0,0 +1,57 @@
+# gateway-gamers.net
+
+Monorepo for the `*.gateway-gamers.net` static sites. Each site is an independent
+Vite + Tailwind v4 + daisyUI project, deployed to its own subdomain, but they
+share a header shell, footer, and hero-carousel images so a logo/photo swap
+doesn't need to happen four times.
+
+## Layout
+
+```
+shared/
+  header.template.html   # full header markup, nav swapped in at build time
+  footer.html             # byte-identical across every site
+  images/                 # logo + carousel photos, one copy
+scripts/
+  render-header.mjs        # shared/header.template.html + sites/<site>/nav.html -> sites/<site>/public/header.html
+sites/
+  40k-rankings/
+  aos-rankings/
+  kingmaker/
+  scouting/
+```
+
+Each `sites/<name>/` is a full Vite project (own `package.json`, `vite.config.js`,
+`src/`, `index.html`). Two things are *not* duplicated per site:
+
+- `public/footer.html` and `public/images` are symlinks into `../../../shared/`.
+- `public/header.html` is generated (gitignored) from `shared/header.template.html`
+  plus that site's own `nav.html` (just its `<li>` nav entries) — run automatically
+  via the `predev`/`prebuild` npm scripts, so `npm run dev` / `npm run build` always
+  regenerate it fresh. Nothing else about the header (carousel, logo, theme toggle)
+  varies per site.
+
+To add a new site's nav, edit `sites/<name>/nav.html`. To change the shared photos,
+logo, footer copy, or header markup/structure, edit under `shared/` once.
+
+## Commands (per site)
+
+```bash
+cd sites/<name>
+npm install
+npm run dev       # http://localhost:5173, regenerates header.html first
+npm run build     # -> dist/
+npm run preview
+```
+
+## Deploy
+
+`.gitlab-ci.yml` at the repo root builds/deploys each site independently
+(path-scoped via `rules: changes:`), plus a `deploy:shared` job that syncs
+`shared/images/` and `shared/footer.html` to
+`/var/www/domains/gateway-gamers.net/shared/` on the webserver — the box
+the GitLab Runner executes on. Every site's nginx server block points
+`/images/` and `/footer.html` at that shared directory via `alias`, so the
+webserver only ever holds one copy of the ~25MB of images. See each
+`sites/<name>/<name>.gateway-gamers.net.conf` for the live nginx reference
+config (applied manually on the box — CI doesn't touch nginx).