fix(core): _restProps falls back to plain-object copy for non-props inputs

[blakeley]

Fixes #8894

Problem

The optimizer emits _restProps for any rest destructure it hoists into a QRL segment, not just component prop destructures. A routeLoader$ such as:

export const useThing = routeLoader$(async () => {
  const { secret, ...rest } = await fetchThing();
  return rest;
});

is compiled to _restProps(await fetchThing(), ["secret"]) (visible in the SSR transform output of the repro below).

But _restProps only knew how to read the _VAR_PROPS / _CONST_PROPS symbols, which exist solely on component props proxies. Given a plain object neither symbol is present, both loops iterate nothing, and the helper returns an empty props proxy. The rest object silently loses every key — no error, no warning, just missing data in the loader payload.

Fix

_restProps now detects a non-props input (both _VAR_PROPS and _CONST_PROPS are undefined) and falls back to native rest-destructure semantics: copy the input's own enumerable keys, minus the omit list, into target and return target itself — a plain object, not a props proxy.

The existing props-proxy path is untouched, so there is no behavior change for component props.

Repro

Minimal reproduction: https://github.com/blakeley/restprops-plain-object-empty

Tests

Added packages/qwik/src/core/shared/utils/prop.unit.ts with four cases, all of which fail on main and pass with the fix:

• plain object {a:1,b:2,c:3} with omit ["a"] → {b:2,c:3}
• plain object with an empty omit list → every key copied
• the result for a plain object is a plain object, not a props proxy
• the provided target is written into and returned

The full packages/qwik/src/core vitest suite is green (2057 passed).

[changeset-bot]

🦋 Changeset detected

Latest commit: b68b1bb

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 5 packages

Name	Type
@qwik.dev/core	Patch
eslint-plugin-qwik	Patch
@qwik.dev/react	Patch
@qwik.dev/router	Patch
create-qwik	Patch

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