fix(web): update diff-card tests for the openFile no-double-resolve contract

The coverage lane caught a regression in the prior commit: FileMutationRow now
passes the tool's raw path to the injected openFile (which resolves against cwd
in apply.ts), but diff-card.spec still asserted the row pre-resolved. Assert on
the raw path instead. Also fix the built-boot diff assertion to match on the
line body and footer text — the `+ ` prefix is a CSS ::before, absent from
textContent.

apps/web/tests/built-boot.snapshot.ts

@@ -112,12 +112,12 @@ it('boots the built plugin graph and renders a fixture session end to end', asyn
   // (the keyed FileMutationRow + DiffBlock), not just the fixture's raw text.
   // The write turn's `hello fixture\n` proves the terminator rule end to end: a
   // trailing newline terminates its line, so the footer reads `+1` (not a
-  // phantom `+2`) and one distinct file.
-  const diffCards = document.querySelectorAll('[data-diff]')
+  // phantom `+2`) and one distinct file. The `+ ` prefix is a CSS ::before, so
+  // it is absent from textContent — assert on the line body and the footer.
+  const diffCards = [...document.querySelectorAll('[data-diff]')]
   expect(diffCards.length).toBeGreaterThan(0)
-  const footers = [...document.querySelectorAll('[data-diff]')]
-    .map(card => card.textContent ?? '')
-  expect(footers.some(text => text.includes('+ hello fixture') && text.includes('+1 -0 · 1 file'))).toBe(true)
+  const footers = diffCards.map(card => card.textContent ?? '')
+  expect(footers.some(text => text.includes('hello fixture') && text.includes('+1 -0 · 1 file'))).toBe(true)
 
   // Every bundle injected its plugin-owned style tag (the loader's CSS path).
   const styleOwners = [...document.head.querySelectorAll('style[data-plugin]')]