fix(app): clear composer text input upon sending on mobile (#3564)

* fix(app): clear mobile composer input on submit

Submitting a prompt on mobile failed to clear the native text input because EditingTextInput.replaceText previously only called setNativeProps({ text }), which is ignored on Fabric and PasteTextInput.

Fix this by:
- Delegating replaceText in EditingTextInputNative to inputRef.current.replaceText when available, clearing via clear() when text is empty, and falling back to setNativeProps.
- Patching @mattermost/react-native-paste-input to expose replaceText(text, selection) backed by native Commands.setTextAndSelection, updating clear() to use live event counts, and preventing useImperativeHandle closures over null refs during initial mount.
- Registering the patch in scripts/postinstall-patches.mjs and adding unit tests for native text input replacement and clearing.

* fix: update nix npm dependency hash

packages/app/src/components/ui/text-input/text-input.native.test.tsx

@@ -0,0 +1,62 @@
+// @vitest-environment jsdom
+import React, { act, createRef } from "react";
+import { createRoot, type Root } from "react-dom/client";
+import { afterEach, beforeEach, describe, expect, it } from "vitest";
+import { EditingTextInput } from "./text-input";
+import type { EditingTextInputHandle } from "./types";
+
+let container: HTMLDivElement | null = null;
+let root: Root | null = null;
+
+beforeEach(() => {
+  container = document.createElement("div");
+  document.body.appendChild(container);
+  root = createRoot(container);
+});
+
+afterEach(() => {
+  if (root && container) {
+    act(() => {
+      root?.unmount();
+    });
+    container.remove();
+  }
+  root = null;
+  container = null;
+});
+
+function noop() {}
+
+describe("EditingTextInputNative", () => {
+  it("clears text via clear() when replaceText receives an empty string", () => {
+    const handleRef = createRef<EditingTextInputHandle>();
+
+    act(() => {
+      root?.render(<EditingTextInput ref={handleRef} initialValue="initial" onChangeText={noop} />);
+    });
+
+    expect(handleRef.current?.getText()).toBe("initial");
+
+    act(() => {
+      handleRef.current?.replaceText("");
+    });
+
+    expect(handleRef.current?.getText()).toBe("");
+  });
+
+  it("updates textRef and text when replaceText receives non-empty text", () => {
+    const handleRef = createRef<EditingTextInputHandle>();
+
+    act(() => {
+      root?.render(<EditingTextInput ref={handleRef} initialValue="hello" />);
+    });
+
+    expect(handleRef.current?.getText()).toBe("hello");
+
+    act(() => {
+      handleRef.current?.replaceText("world", { start: 0, end: 5 });
+    });
+
+    expect(handleRef.current?.getText()).toBe("world");
+  });
+});

packages/app/src/components/ui/text-input/text-input.tsx

@@ -11,7 +11,9 @@ type NativeInput = (TextInput | PasteTextInputInstance) & {
   blur(): void;
   focus(): void;
   isFocused(): boolean;
-  setNativeProps(props: { text: string; selection?: { start: number; end: number } }): void;
+  clear?(): void;
+  replaceText?(text: string, selection?: { start: number; end: number }): void;
+  setNativeProps?(props: { text?: string; selection?: { start: number; end: number } }): void;
   setSelection?(start: number, end: number): void;
   getNativeRef?(): unknown;
 };
@@ -39,7 +41,18 @@ export const EditingTextInput = forwardRef<EditingTextInputHandle, EditingTextIn
       getText: () => textRef.current,
       replaceText: (nextText, selection) => {
         textRef.current = nextText;
-        inputRef.current?.setNativeProps({ text: nextText, ...(selection ? { selection } : {}) });
+        if (inputRef.current?.replaceText) {
+          inputRef.current.replaceText(nextText, selection);
+          return;
+        }
+        if (nextText === "") {
+          inputRef.current?.clear?.();
+        } else {
+          inputRef.current?.setNativeProps?.({
+            text: nextText,
+            ...(selection ? { selection } : {}),
+          });
+        }
         if (selection) inputRef.current?.setSelection?.(selection.start, selection.end);
       },
       getNativeRef: () => inputRef.current?.getNativeRef?.() ?? inputRef.current,