Upgrade React to v19.2.3 (and fix type errors in useRef hooks)

[Copilot]

React 19 requires explicit initial values for useRef. Previously valid patterns like useRef<HTMLElement>() now fail type checking.

Changes

React upgrade

• Upgraded react and react-dom to ^19.2.3
• Upgraded @types/react and @types/react-dom to ^19.2.3 (matching versions with runtime packages, using caret prefix per project convention)

Type fixes

• Added explicit undefined initial values to useRef<HTMLElement>() calls in ModelAlertsResults.tsx and MethodRow.tsx
• Updated useScrollIntoView signature to accept RefObject<E | null> instead of RefObject<HTMLElement>
• Updated ref prop types in AlertTableResultRow, AlertTablePathRow, and AlertTablePathNodeRow to include | null
• Updated test mocks to match new ref types

Configuration

• Fixed ESLint config: ensured reactHooks.configs.flat['recommended-latest'] is used for flat config compatibility (the non-flat config uses old eslintrc format which is incompatible with ESLint flat config)

Example

Before:

const ref = useRef<HTMLElement>();  // Type error in React 19

After:

const ref = useRef<HTMLElement | undefined>(undefined);  // OK

Remember to update the changelog if there have been user-facing changes!

Original prompt

Update the codebase in /extensions/ql-vscode and any affected parts to address all type errors caused by the React v19.2 upgrade, as visible in the CI checks. Specifically, address issues involving useRef now requiring a default value (so types like useRef() are no longer allowed; instead, useRef<T | undefined>(undefined)). Update downstream code to handle T | undefined as necessary, including code expecting T or directly accessing ref.current. Make sure to reference Robert's comments in #4131 for more guidance and code locations. Ensure all CI tests are passing and the extension works as expected after the fixes.

This pull request was created from Copilot chat.

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