fix: guard input-template render effect against unstable content

[timurbazhirov]

Summary

ExecutionUnit's effect that re-renders input-template content whenever renderingContext changes always wrote the freshly-rendered content back via onUnitInputRenderedUpdate, even when it exactly matched what was already stored:

useEffect(() => {
    if (!renderingContext) return;
    unit.input.forEach((inputRow, index) => {
        const rendered = renderTextWithSubstitutes(inputRow.template.content, renderingContext);
        onUnitInputRenderedUpdate(index, rendered); // always called
    });
}, [renderingContext]);

onUnitInputRenderedUpdate always produces a brand-new unit object via onUpdate(...). If anything upstream recomputes renderingContext from the updated unit (even to a referentially-new-but-otherwise-equal value), this effect re-fires — and for any input whose rendered output isn't perfectly stable across renders, this creates an infinite renderingContext → onUpdate → new renderingContext loop, crashing with React's "Maximum update depth exceeded".

Reproduced live: selecting the pp.x or average.x executables (unlike the default pw.x) in the unit editor crashes the whole app with this exact error, immediately on opening the Flavor select.

Fix

Only call onUnitInputRenderedUpdate when the newly-rendered content actually differs from inputRow.rendered, breaking the loop regardless of why a given input's rendered output is unstable.

Test plan

• npm run build and npm test (20/20 passing)
• Reproduced and confirmed the crash live against a deployed environment (Cypress spec unit-editor-choose-espresso-executable-and-flavor.feature, examples using pp.x/average.x)

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