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feat(compiler): emit the spread/ssrElement sources array for multi-source element spreads (#3423)

Native elements with several spread sources compile to the runtimes' array
form instead of a mergeProps() call, in DOM and SSR output, in both the
Babel plugin and the native compiler:

  <div id="x" {...a} {...b}>
  → spread(el, [{ id: "x" }, a, b], skipChildren)          (dom)
  → ssrElement("div", [{ id: "x" }, a, b], children, id)   (ssr)

The runtimes read the sources directly — later sources win per key, only
the winning source is read — so there is no merge proxy to build and walk
once. A reactive spread is a plain thunk called inside the tracking scope:
no memo, so no hydration id on either side. That also retires the
hydratable SSR `() => mergeProps(...)` wrapper, which existed only to order
the merge memo's id after the element's key; a lone dynamic spread left
behind once the server drops on*/prop:/children keys now passes through as
the props thunk itself. A lone spread still passes straight through
(#3105). Universal output is unchanged; its runtime spread has no array
form yet.

Requires @solidjs/web with the array forms (#3418, #3419). Fixtures
regenerated for both compilers; the recorded cross-mode Babel/Oxc
divergences changed only in context (mergeProps → array).

Co-authored-by: Cursor <cursoragent@cursor.com>

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