render: support streamed framework hydration

Make attribute maps live, preserve parser script execution state, and expose
element scrolling used by React commit callbacks. Connect fallback web streams
so React Router and Remix hydration payloads flow through codec transforms.

crates/obscura-browser/src/page.rs

@@ -679,6 +679,22 @@ impl Page {
             None => return,
         };
 
+        // HTML scripts have an "already started" flag. Mark every
+        // parser-discovered script before running page code so React/Next
+        // hydration can move or hoist those nodes without appendChild
+        // executing them a second time.
+        if let Some(js) = &mut self.js {
+            let ids = all_scripts
+                .iter()
+                .map(|script| script.nid.to_string())
+                .collect::<Vec<_>>()
+                .join(",");
+            let _ = js.execute_script(
+                "<parser-scripts>",
+                &format!("globalThis.__markParserScripts([{}]);", ids),
+            );
+        }
+
         let mut regular = Vec::new();
         let mut deferred = Vec::new();
         let mut async_scripts = Vec::new();