fix(browser): scope evaluateWithArgs declarations in an IIFE

[MatrixA]

Bug

opencli browser <session> upload <ref> <file> throws on the second
invocation against the same page:

✖  SyntaxError: Identifier 'markerAttr' has already been declared

Reloading the page does not clear the error — the same execution context is reused.

Minimal repro

opencli browser s open https://www.w3schools.com/howto/howto_html_file_upload_button.asp
opencli browser s wait selector "input[type=file]"
opencli browser s find --css "input[type=file]"   # note the ref, e.g. 1
opencli browser s upload 1 /tmp/any.png           # works (or fails with not_file_input)
opencli browser s upload 1 /tmp/any.png           # SyntaxError: 'markerAttr' has already been declared

Root cause

BasePage.uploadFiles calls evaluateWithArgs with { markerAttr, markerValue }.
evaluateWithArgs (src/browser/base-page.ts:160-170) emits:

const markerAttr = "data-opencli-upload-target";
const markerValue = "...";
(() => { ... el.setAttribute(markerAttr, markerValue); ... })()

wrapForEval correctly classifies this as a "bare expression" and sends it as-is to
Runtime.evaluate. The const declarations land at script top level. With the bridge
reusing the same execution context, the second call hits a duplicate-binding
SyntaxError. Same applies to every other evaluateWithArgs callsite that uses fixed
keys — upload just happens to be the easiest to trip because it always reuses
markerAttr / markerValue.

Fix

Wrap the declarations and the caller-supplied expression in an IIFE so the bindings
are block-scoped. wrapForEval already recognizes this shape as already-IIFE and
forwards it unchanged. The body is parenthesized and returned so Promise return
values are preserved (CDP awaits via awaitPromise: true).

- return this.evaluate(`${declarations}\n${js}`);
+ return this.evaluate(`(() => { ${declarations}\nreturn (${js}); })()`);

Verification

• New unit test BasePage.evaluateWithArgs > wraps declarations and body in an IIFE …
  asserts the emitted script is IIFE-wrapped and returns the inner expression.
• npx vitest run --project unit → 1139 passed, 1 skipped.
• npm run typecheck → clean.
• End-to-end against a real page: two consecutive browser upload calls on the same
  session no longer throw the markerAttr SyntaxError. (Whatever underlying
  DOM.setFileInputFiles permission errors a page may still surface are independent
  of this fix.)

Notes

• All current evaluateWithArgs callsites pass an expression ((() => …)() or
  (async () => …)()), so the return (${js}); wrapper is safe for every caller.
• The JSDoc on evaluateWithArgs is updated to call out the IIFE requirement so future
  refactors don't silently regress it.