refactor: retire wheelReport JSON-RPC fallback

Per PR review (#1462): the Cloud SPA is versioned and LAN access
always serves a matching Go API and JS SPA, so the backwards-compat
fallback is unnecessary. Drop the `rpcHidReady ? binary : send(...)`
branch from getMouseWheelHandler — always use the binary path —
and remove the `wheelReport` entry from the JSON-RPC handler map.
The binary 0x04 dispatch and rpcWheelReport itself stay; the
function is now reached only via handleHidRPCMessage.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: mcuelenaere

jsonrpc.go

@@ -1256,7 +1256,6 @@ var rpcHandlers = map[string]RPCHandler{
 	"keypressReport":             {Func: rpcKeypressReport, Params: []string{"key", "press"}},
 	"absMouseReport":             {Func: rpcAbsMouseReport, Params: []string{"x", "y", "buttons"}},
 	"relMouseReport":             {Func: rpcRelMouseReport, Params: []string{"dx", "dy", "buttons"}},
-	"wheelReport":                {Func: rpcWheelReport, Params: []string{"wheelY", "wheelX"}},
 	"getVideoState":              {Func: rpcGetVideoState},
 	"getUSBState":                {Func: rpcGetUSBState},
 	"unmountImage":               {Func: rpcUnmountImage},

ui/src/hooks/useMouse.ts

@@ -138,20 +138,15 @@ export default function useMouse() {
 
       if (wheelY === 0 && wheelX === 0) return;
 
-      if (rpcHidReady) {
-        reportWheelEvent(wheelY, wheelX);
-      } else {
-        // kept for backward compatibility
-        send("wheelReport", { wheelY, wheelX });
-      }
+      reportWheelEvent(wheelY, wheelX);
 
       // Apply blocking delay based of throttling settings
       if (scrollThrottling && !blockWheelEvent) {
         setBlockWheelEvent(true);
         setTimeout(() => setBlockWheelEvent(false), scrollThrottling);
       }
     },
-    [send, reportWheelEvent, rpcHidReady, blockWheelEvent, scrollThrottling, invertScroll],
+    [reportWheelEvent, blockWheelEvent, scrollThrottling, invertScroll],
   );
 
   const resetMousePosition = useCallback(() => {