Consolidate all moonweb sites into single Eleventy config

- Single eleventy.config.js at root with computed pathPrefix per section
- Accent colors inlined in base.njk (no per-site theme.css needed)
- Hub pages output at root via explicit permalinks
- Per-section sitemaps with tag-based collections
- .eleventyignore excludes stefankoelle, timecapsule, markdown files
- Deleted: 5 per-site configs, merge script
- Simplified: package.json (single build/dev commands)
- Simplified: GitHub Actions workflow (no matrix, no merge job)
- Fixed: parent links for sub-site detail pages

.eleventyignore

@@ -0,0 +1,17 @@
+stefankoelle/
+timecapsule/
+scripts/
+.tmp/
+
+# Root markdown files (not templates)
+/*.md
+
+# Hub static redirect files (handled by passthrough copy)
+hub/hardware.html
+hub/users.html
+hub/index2.html
+hub/index3.html
+hub/new.html
+hub/links.html
+hub/infos.html
+hub/start.html