fix(compat): avoid mutating user-provided style objects when appending px

[JSap0914]

Bug

handleDomVNode in compat/src/render.js mutates the style object supplied by the caller when appending px to numeric values:

// before
if (i === "style" && typeof value === "object") {
    for (let key in value) {
        if (typeof value[key] === "number" && !IS_NON_DIMENSIONAL.test(key)) {
            value[key] += "px"; // ← mutates props.style in place
        }
    }
}

value is a direct reference to props[i] (the original object passed by the user). After this loop the caller's object is permanently modified—margin: 10 becomes margin: "10px"—which is an unexpected side effect.

Fix

Shallow-copy the style object before the loop so mutations stay local to normalizedProps:

value = assign({}, value);

The px-append behaviour and the rendered output are unchanged; only the caller's object is now left untouched.

Verification

npx vitest run compat/test/browser/render.test.jsx

New test: "should not mutate the original style object when appending px" — this test failed before the fix (style.margin was mutated to "10px") and passes after it.

All 46 existing compat-render tests continue to pass; full suite: 1242 passed, 12 skipped across 101 test files.

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[JoviDeCroock]

A code golfing suggestion

[JoviDeCroock]

Suggested change

	let cloned = false;
	let cloned;

[JoviDeCroock]

Suggested change

	value = assign({}, value);
	cloned = true;
	cloned = value = assign({}, value);