Address @qa review on PR #12 (issue #11)

- index.html: replace Image() probe with fetch(no-cors) + AbortController
  timeout. fetch resolves for any network response (incl. 4xx/5xx) so
  resolve -> 'up', reject/timeout -> 'down'. Fixes the bug where 401/404
  services were marked green.
- services.json: add Homepage service under 'dev' (was missing; the
  homepage is one of the public homelab services). Now 21 services.
- services.json: fix ethereum category icon (' Ξ' -> 'Ξ') leading space.
- .gitignore (new): ignore /.playwright-mcp/ and services-page.png.
- git rm --cached the three stray dev artifacts so they leave the repo.

.gitignore

@@ -0,0 +1,6 @@
+# Playwright MCP scratch files (local browser sessions)
+/.playwright-mcp/
+
+# Local screenshots from manual testing
+services-page.png
+*.screenshot.png