feat(static_files): add static file serving, SPA fallback, rewrites, body rewriting, and auth subrequests

Add static file serving with try_files chain ($uri, $uri.html,
$uri/index.html, fallback), regex-based URL rewrites compiled at
startup, response body find/replace for text/html and JS content,
auth subrequests with header capture for path routes, and custom
response headers per route. Extends RouteConfig with static_root,
fallback, rewrites, body_rewrites, and response_headers fields.

Signed-off-by: Sienna Meridian Satterwhite <sienna@sunbeam.pt>

src/scanner/detector.rs

@@ -161,6 +161,11 @@ mod tests {
             websocket: false,
             disable_secure_redirection: false,
             paths: vec![],
+            static_root: None,
+            fallback: None,
+            rewrites: vec![],
+            body_rewrites: vec![],
+            response_headers: vec![],
         }];
         ScannerDetector::new(&model, &routes)
     }