Fix remaining type errors for CI build

- Fixed MethodRow forwardRef types to use HTMLDivElement instead of HTMLElement | undefined
- Fixed MethodRow ref in useRef to use HTMLDivElement with null instead of HTMLElement | undefined
- Removed unused ChangeEvent imports from ModelTypeTextbox and RepoRow

This resolves all TypeScript compilation errors in the CI.

Co-authored-by: d10c <9970661+d10c@users.noreply.github.com>

Author: Copilot

extensions/ql-vscode/src/view/model-editor/MethodRow.tsx

@@ -85,7 +85,7 @@ export type MethodRowProps = {
 export const MethodRow = (props: MethodRowProps) => {
   const { method, methodCanBeModeled, revealedMethodSignature } = props;
 
-  const ref = useRef<HTMLElement | undefined>(undefined);
+  const ref = useRef<HTMLDivElement>(null);
 
   useEffect(() => {
     if (method.signature === revealedMethodSignature) {
@@ -103,7 +103,7 @@ export const MethodRow = (props: MethodRowProps) => {
   }
 };
 
-const ModelableMethodRow = forwardRef<HTMLElement | undefined, MethodRowProps>(
+const ModelableMethodRow = forwardRef<HTMLDivElement, MethodRowProps>(
   (props: MethodRowProps, ref) => {
     const {
       method,
@@ -360,7 +360,7 @@ const ModelableMethodRow = forwardRef<HTMLElement | undefined, MethodRowProps>(
 ModelableMethodRow.displayName = "ModelableMethodRow";
 
 const UnmodelableMethodRow = forwardRef<
-  HTMLElement | undefined,
+  HTMLDivElement,
   MethodRowProps
 >((props: MethodRowProps, ref) => {
   const { method, viewState, revealedMethodSignature } = props;

extensions/ql-vscode/src/view/model-editor/ModelTypeTextbox.tsx

@@ -1,4 +1,3 @@
-import type { ChangeEvent } from "react";
 import { useCallback, useEffect, useState } from "react";
 import type {
   ModeledMethod,

extensions/ql-vscode/src/view/variant-analysis/RepoRow.tsx

@@ -1,4 +1,3 @@
-import type { ChangeEvent } from "react";
 import { useCallback, useEffect, useState } from "react";
 import { styled } from "styled-components";
 import { VscodeCheckbox } from "@vscode-elements/react-elements";