fix(frontend): resolve ESLint react-hooks/exhaustive-deps warning in ReportViewer

[Copilot]

ESLint with --max-warnings 0 was failing CI because getChartHeight — a function that closes over isPhone/isTablet state — was used inside a useEffect but absent from its dependency array.

Changes

• ReportViewer.tsx: Convert getChartHeight from a plain inline function to useCallback with [isPhone, isTablet] deps; add it to the chart-building useEffect dep array

// Before
function getChartHeight(base: number): number { ... }
useEffect(() => { ... }, [data]);

// After
const getChartHeight = useCallback((base: number): number => { ... }, [isPhone, isTablet]);
useEffect(() => { ... }, [data, getChartHeight]);