feat(docs): add GitHub Pages landing page with SEO and source-verified content

- Self-contained landing page (HTML/CSS/JS) under docs/ for static.21no.de
- Dark theme with particle animations, tabbed layouts, scroll-reveal
- All technical claims verified against Go source (cache benchmarks, TLS config, security model, config defaults)
- SEO: canonical URL, Open Graph, Twitter Cards, JSON-LD structured data, sitemap.xml, robots.txt
- Semantic HTML: proper heading hierarchy, main/nav landmarks, aria-labelledby
- OG image (SVG) matching site design for social sharing
- MIT LICENSE file added

Author: jkyberneees

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 21no.de
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

docs/index.html

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+User-agent: *
+Allow: /
+Sitemap: https://static.21no.de/sitemap.xml