fix(chrome): name a web field by its hint, not its CSS class

visibleLabel reads hintText first for an editable element. The dump never
emitted it, so an empty web input fell through text, description and
descendant text to its class name, and the model was shown an identifier no
user can read on exactly the fields a labelling experiment varies.

Same ladder as fieldHint in web-runtime.ts, so one field is named one way on
both hosts.

Claude-Session: https://claude.ai/code/session_01A5KmftdEJ49A9z5mF5ESrX

internal/driver/chrome/driver_test.go

@@ -306,6 +306,79 @@ func TestHierarchy_ScrollableAttribute(t *testing.T) {
 	}
 }
 
+// TestHierarchy_HintTextNamesAnEditableField covers the attribute visibleLabel
+// (internal/verifier/llm.go) reads FIRST for an editable element. Without it a
+// web field reached the model named by its CSS class, an identifier no user can
+// read, on exactly the channel the label-source experiment varies. The ladder is
+// fieldHint's in pkg/spec/src/web-runtime.ts, rung for rung.
+func TestHierarchy_HintTextNamesAnEditableField(t *testing.T) {
+	const html = `<body>` +
+		`<label id="amount-label" for="amount">Amount</label>` +
+		`<input id="amount" placeholder="0.00" name="amount-field">` +
+		`<input id="search" aria-label="Search" placeholder="Type here" name="q">` +
+		`<label id="note-label" for="note"> </label>` +
+		`<input id="note" placeholder="What's this for?" name="note-field">` +
+		`<input id="reference" name="reference-field">` +
+		`<input id="unnamed">` +
+		`<input id="agree" type="checkbox" placeholder="ignored">` +
+		`<button id="go" placeholder="ignored">go</button>` +
+		`</body>`
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.Header().Set("Content-Type", "text/html")
+		_, _ = w.Write([]byte(html))
+	}))
+	defer server.Close()
+
+	d := New()
+	defer d.Terminate(context.Background())
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+	if err := d.Launch(ctx, server.URL, false, nil); err != nil {
+		t.Fatalf("Launch: %v", err)
+	}
+	dump, err := d.Hierarchy(ctx)
+	if err != nil {
+		t.Fatalf("Hierarchy: %v", err)
+	}
+
+	type node struct {
+		Attributes map[string]string `json:"attributes"`
+		Children   []node            `json:"children"`
+	}
+	var root node
+	if err := json.Unmarshal([]byte(dump), &root); err != nil {
+		t.Fatalf("unmarshal hierarchy: %v", err)
+	}
+	hintByID := map[string]string{}
+	var walk func(n node)
+	walk = func(n node) {
+		if id := n.Attributes["resource-id"]; id != "" {
+			hintByID[id] = n.Attributes["hintText"]
+		}
+		for _, c := range n.Children {
+			walk(c)
+		}
+	}
+	walk(root)
+
+	for _, tc := range []struct {
+		id   string
+		want string
+	}{
+		{"search", "Search"},
+		{"amount", "Amount"},
+		{"note", "What's this for?"},
+		{"reference", "reference-field"},
+		{"unnamed", ""},
+		{"agree", ""},
+		{"go", ""},
+	} {
+		if hintByID[tc.id] != tc.want {
+			t.Errorf("%q: hintText = %q, want %q", tc.id, hintByID[tc.id], tc.want)
+		}
+	}
+}
+
 // TestRunCtx_CallerCancelPropagates confirms that cancelling the caller's
 // context cancels the chromedp-bound context returned by runCtx. This is the
 // channel by which step deadlines and Ctrl-C reach in-flight CDP calls.