fix: serialize input RPCs to preserve byte order (#3164)

ControllerInputCommand was fire-and-forget, letting wavesrv process
concurrent calls on separate goroutines and reorder bytes before they
reached the PTY. Under fast IME composition followed by ASCII input
this produced visible corruption like "이 런문제" instead of
"이런 문제" — the same user-visible symptom as #3164 even after the
xterm-side IME fix earlier in this PR.

Chain calls through a Promise queue so each RPC awaits the previous,
preserving dispatch order all the way to the PTY.

Author: hyeonjinyoon

frontend/app/view/term/term-model.ts

@@ -506,9 +506,16 @@ export class TermViewModel implements ViewModel {
         }
     }
 
+    // Serialize input RPCs to preserve order. Without this, fire-and-forget
+    // calls can be processed concurrently on the backend and reorder bytes
+    // (especially visible with fast IME composition followed by ASCII input).
+    inputQueue: Promise<void> = Promise.resolve();
+
     sendDataToController(data: string) {
         const b64data = stringToBase64(data);
-        RpcApi.ControllerInputCommand(TabRpcClient, { blockid: this.blockId, inputdata64: b64data });
+        this.inputQueue = this.inputQueue
+            .then(() => RpcApi.ControllerInputCommand(TabRpcClient, { blockid: this.blockId, inputdata64: b64data }))
+            .catch(() => {});
     }
 
     setTermMode(mode: "term" | "vdom") {