v0.35.1: performance, AGPL licensing and documentation overhaul

- Web Server reads static files inline; proxy middleware chain flattened
- About window with license summary and project links; AGPL-3.0-or-later
- Rewritten documentation: feature list, screenshots, performance guide
- Fix false spikes in per-Vhost request-rate charts

src/http3/body.rs

@@ -9,11 +9,11 @@ fn invalid_headers(headers: &HeaderMap) -> bool {
     .iter()
     .any(|name| headers.contains_key(*name))
         || headers
-            .get_all("te")
+            .get_all(::http::header::TE)
             .iter()
             .any(|value| value.as_bytes() != b"trailers")
-        || headers.get_all("content-length").iter().count() > 1
-        || headers.get("content-length").is_some_and(|value| {
+        || headers.get_all(::http::header::CONTENT_LENGTH).iter().count() > 1
+        || headers.get(::http::header::CONTENT_LENGTH).is_some_and(|value| {
             value
                 .to_str()
                 .ok()