docs: drop the README limit the EIP-1193 code fix removed (closes #285)

The End-to-End Tests section listed, as the third of three standing limits
of the dApp coverage, the EIP-1193 error code not surviving the last hop
into the page. That stopped being true when `9dcd875` landed
(#274): the provider now rejects
with a `ProviderRpcError` carrying `code`, and the e2e suite asserts the
code on the page as well as on the wire.

The other two limits are still accurate against the current code and are
left alone.

README.md

@@ -185,17 +185,14 @@ to the background — with the message that would carry it required to be presen
 so that check cannot pass by observing nothing. That last one is the standing
 floor under [#157](https://git.eeqj.de/sneak/AutistMask/issues/157).
 
-Three limits of that coverage, none of them papered over. The RPC is stubbed
+Two limits of that coverage, neither of them papered over. The RPC is stubbed
 throughout, so this is **not** a real dApp against a real network with real
 funds; that remains a human pass before 1.0.0. The site-connection prompt is
 raised through `chrome.action.openPopup()`, and headless Chromium's
 browser-action popup is not a page Playwright can see or click, so that one
 prompt is driven at the URL the extension itself puts on the action — the same
 page and the same approval id, but whether a real toolbar click shows it is not
-observable here. And the EIP-1193 error code does not survive the last hop: the
-rejection that crosses the boundary carries code 4001 and is asserted to, but
-`src/content/inpage.js` rebuilds it as `new Error(message)`, so the calling page
-catches an error with no `code` property.
+observable here.
 
 Any test that drives a failure path on purpose declares the `console.error` it
 is about to provoke, via `errors.expect()`. That is not a mute: the declaration