fix(js): isolate startup binding failures

Keep the public runtime API available and report state, binding, and SSE startup errors independently so one startup failure cannot hide the runtime object or other roots.

req: runtime/002

hemx-js/runtime/hemx.js

@@ -793,10 +793,18 @@
     roots().forEach((root) => {
       try {
         bootstrapState(root);
+      } catch (error) {
+        emit(root, "hemx:state-error", String(error));
+      }
+      try {
         bindRoot(root);
+      } catch (error) {
+        emit(root, "hemx:bind-error", String(error));
+      }
+      try {
         bindSse(root);
       } catch (error) {
-        emit(root, "hemx:error", String(error));
+        emit(root, "hemx:sse-error", String(error));
       }
     });
     try {

hemx-js/tests/runtime.rs

@@ -11,7 +11,9 @@ fn runtime_exposes_debug_api_before_startup_side_effects() {
         .expect("runtime starts after declaration");
     assert!(api < start);
     assert!(source.contains("try {\n        bootstrapState(root);"));
-    assert!(source.contains("emit(root, \"hemx:error\", String(error));"));
+    assert!(source.contains("emit(root, \"hemx:state-error\", String(error));"));
+    assert!(source.contains("try {\n        bindRoot(root);"));
+    assert!(source.contains("emit(root, \"hemx:bind-error\", String(error));"));
 }
 
 #[test]