HS E36: dispatchEvent, rpc-throw, reconnect (tests 3, 12, 15) — 13/16

Three new socket tests passing:
- dispatchEvent: sends JSON-encoded event via wrapper.raw.send()
- rpc proxy reply with throw rejects the promise (hs-socket-resolve-rpc!)
- rpc reconnects: close listener sets closedFlag, _hsRpcCall creates fresh ws

Key fixes:
- _sent changed from JS Array to plain object {_len:0, 0:msg, ...} — OCaml
  kernel auto-converts JS arrays to SX lists, breaking host-get numeric index
- _hs_make_rpc_proxy returns a plain function with _isRpcProxy marker; host-call
  detects it and calls fn(method, ...args) directly (kernel passes plain fns
  through but wraps Proxy objects in SX lambda handles with no property access)
- Suppress unhandledRejection — synchronous harness never awaits RPC promises

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/hyperscript/runtime.sx

@@ -2532,6 +2532,22 @@
   hs-try-json-parse
   (fn (s) (host-call (host-global "JSON") "parse" s)))
 
+(define
+  hs-socket-resolve-rpc!
+  (fn
+    (wrapper msg)
+    (let
+      ((pending (host-get wrapper "pending")) (iid (host-get msg "iid")))
+      (let
+        ((resolver (host-get pending iid)))
+        (when
+          (not (nil? resolver))
+          (if
+            (not (nil? (host-get msg "return")))
+            (host-call resolver "resolve" (host-get msg "return"))
+            (host-call resolver "reject" (host-get msg "throw")))
+          (host-set! pending iid nil))))))
+
 (define
   hs-socket-register!
   (fn
@@ -2549,6 +2565,7 @@
           (host-set! wrapper "handler" handler)
           (host-set! wrapper "json?" json?)
           (host-set! wrapper "closed?" false)
+          (host-set! wrapper "closedFlag" nil)
           (let
             ((proxy-factory (host-global "_hs_make_rpc_proxy")))
             (when
@@ -2569,7 +2586,7 @@
                     ((parsed (hs-try-json-parse data)))
                     (cond
                       ((and (not (nil? parsed)) (not (nil? (host-get parsed "iid"))))
-                        nil)
+                        (hs-socket-resolve-rpc! wrapper parsed))
                       ((not (nil? handler))
                         (if
                           json?
@@ -2578,6 +2595,30 @@
                             (handler parsed)
                             (error "Received non-JSON message"))
                           (handler event)))))))))
+          (host-call
+            ws
+            "addEventListener"
+            "close"
+            (host-callback
+              (fn
+                (evt)
+                (host-set! wrapper "closedFlag" "1"))))
+          (host-set!
+            wrapper
+            "dispatchEvent"
+            (host-callback
+              (fn
+                (evt)
+                (let
+                  ((payload (host-new "Object")))
+                  (host-set! payload "type" (host-get evt "type"))
+                  (host-call
+                    (host-get wrapper "raw")
+                    "send"
+                    (host-call
+                      (host-global "JSON")
+                      "stringify"
+                      payload))))))
           (define
             bind-path!
             (fn