refactor(http/unstable): default route export to routeLinear

The radix router is brand new; keep `route` bound to the
better-tested `routeLinear` while it matures. Users who want the
radix optimizations opt in via the `routeRadix` named export.

Author: esroyo

http/unstable_route.ts

@@ -28,7 +28,7 @@ export type Handler = (
 ) => Response | Promise<Response>;
 
 /**
- * Route configuration for {@linkcode routeRadix}.
+ * Route configuration for {@linkcode route}.
  *
  * @experimental **UNSTABLE**: New API, yet to be vetted.
  */
@@ -459,4 +459,4 @@ export function routeRadix(
   };
 }
 
-export { routeRadix as route };
+export { routeLinear as route };