ci: spell-check site copy with codespell (closes #14)

Public-facing marketing copy had no spell check — a typo ships silently.

- .codespellrc: scan the repo (skipping build output, node_modules, binaries,
  and the generated data/releases.json).
- .codespell-ignore: project dictionary for crypto/Monero/Tari jargon
  (monerod, pplns, p2pool, tari, xvb, onion, stratum, xmrig, …).
- ci.yml: new "spell" job runs codespell (pinned 2.4.2 via pipx).
- CONTRIBUTING: document running it locally and where to allow-list terms.

Optional Vale prose-lint from the issue is deferred — codespell covers the
spelling acceptance; Vale can land later as a non-blocking follow-up.

Verified locally: codespell clean over the whole repo; prettier/markdownlint
clean; zizmor clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: VijitSingh97

.codespell-ignore

@@ -0,0 +1,11 @@
+monerod
+pplns
+p2pool
+tari
+xvb
+onion
+pithead
+rigforge
+stratum
+tor
+xmrig

.codespellrc

@@ -0,0 +1,5 @@
+[codespell]
+# Spell-check public-facing copy and docs. https://github.com/codespell-project/codespell
+# Crypto/Monero/Tari jargon (XMR, monerod, PPLNS, Tari, …) lives in .codespell-ignore.
+skip = .git,node_modules,public,resources,package-lock.json,data/releases.json,*.svg,*.png,*.ico,*.woff,*.woff2
+ignore-words = .codespell-ignore

.github/workflows/ci.yml

@@ -72,3 +72,15 @@ jobs:
         run: npm run format:check
       - name: markdownlint
         run: npm run lint:md
+
+  spell:
+    name: Spell check (codespell)
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
+        with:
+          persist-credentials: false # zizmor: artipacked
+      # pipx is preinstalled on ubuntu runners. Config + dictionary: .codespellrc / .codespell-ignore.
+      - name: Run codespell
+        run: pipx run codespell==2.4.2 .

CONTRIBUTING.md

@@ -35,6 +35,10 @@ not in the templates. See the [README](README.md#where-the-content-lives) for th
 
 4. Update the README or other docs for any user-facing change.
 
+CI also runs Prettier + markdownlint (`npm run lint`) and a spell check. Run the spell check
+locally with `pipx run codespell .` — domain jargon (XMR, monerod, PPLNS, Tari, …) is allow-listed
+in [`.codespell-ignore`](.codespell-ignore); add new terms there if a real word is flagged.
+
 ## Secret scanning
 
 CI runs [gitleaks](https://github.com/gitleaks/gitleaks) over the full history on every push and PR,