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/cache/lookup/hot.rs

@@ -87,8 +87,7 @@ impl Cache {
                 if skip_compression {
                     response.extensions_mut().insert(crate::compression::Skip);
                 }
-                response.headers_mut().insert(
-                    "age",
+                response.headers_mut().insert(::http::header::AGE,
                     HeaderValue::from_str(&age.to_string()).expect("integer header"),
                 );
                 self.domain_stats
@@ -285,8 +284,7 @@ impl Cache {
         if entry.skip_compression {
             response.extensions_mut().insert(crate::compression::Skip);
         }
-        response.headers_mut().insert(
-            "age",
+        response.headers_mut().insert(::http::header::AGE,
             HeaderValue::from_str(&age.to_string()).expect("integer header"),
         );
         self.domain_stats