fix: address the Maps search box by id, and re-prove Phase 5

The Maps omnibox hint rotates: it read "Search here" in the Phase 5 run and
"Try petrol stations, ATMs" in the AUD-128 re-verification, so the recipe's
text match on it failed. The resource id does not rotate.

- internal/ui: add Find/FindID and the "id:" selector; Find dispatches an
  id: selector to the resource id and everything else to text as before.
- internal/recipe: wait/tap/wait_gone/tap_if and the tap helper use Find, so a
  recipe may name a resource id. Guards stay text-only.
- recipes/maps_navigate.recipe: wait/tap id:search_omnibox_text_box.
- tests for the id selector; docs and README updated.

internal/ui/dump_test.go

@@ -99,6 +99,59 @@ func TestPickBestMatchRejectsDisabledOnly(t *testing.T) {
 	}
 }
 
+// The Maps search box keeps a stable resource id but a rotating label, so it is
+// addressed with the "id:" selector. This covers the full and short id, the
+// prefix dispatch, and that a plain selector is still matched by text.
+const sampleSelectorDump = `<?xml version='1.0' encoding='UTF-8' standalone='yes' ?>
+<hierarchy rotation="0">
+  <node index="0" text="" resource-id="com.google.android.apps.maps:id/search_omnibox_text_box" class="android.widget.EditText" package="com.google.android.apps.maps" content-desc="Try petrol stations, ATMs" clickable="true" enabled="true" bounds="[31,142][663,268]"/>
+  <node index="1" text="Search" resource-id="com.example:id/other" class="android.widget.TextView" package="com.example" clickable="true" enabled="true" bounds="[0,0][10,10]"/>
+</hierarchy>`
+
+func parseSelectorSample(t *testing.T) *Hierarchy {
+	t.Helper()
+	h, err := parseHierarchy([]byte(sampleSelectorDump))
+	if err != nil {
+		t.Fatalf("parseHierarchy: %v", err)
+	}
+	return h
+}
+
+func TestFindIDSelector(t *testing.T) {
+	h := parseSelectorSample(t)
+
+	// Full resource id, and the short name after the "/".
+	for _, sel := range []string{
+		"id:search_omnibox_text_box",
+		"id:com.google.android.apps.maps:id/search_omnibox_text_box",
+	} {
+		matches := h.Find(sel, false)
+		if len(matches) != 1 {
+			t.Fatalf("Find(%q): want 1 match, got %d", sel, len(matches))
+		}
+		if matches[0].Class != "android.widget.EditText" {
+			t.Fatalf("Find(%q) matched %q", sel, matches[0].Class)
+		}
+	}
+
+	// Exact matching of the short id.
+	if got := len(h.Find("id:search_omnibox_text_box", true)); got != 1 {
+		t.Fatalf("exact id: want 1, got %d", got)
+	}
+	// A plain selector is not diverted to the id match.
+	if got := len(h.Find("search_omnibox_text_box", false)); got != 0 {
+		t.Fatalf("plain text must not match a resource id, got %d", got)
+	}
+	// Text still works through Find.
+	if got := len(h.Find("Search", true)); got != 1 {
+		t.Fatalf("text via Find: want 1, got %d", got)
+	}
+	// An unknown id is a clean miss, not a fallthrough to text.
+	if got := h.Find("id:no_such_id", false); len(got) != 0 {
+		t.Fatalf("unknown id: want 0, got %d", len(got))
+	}
+}
+
 func TestEscapeInputText(t *testing.T) {
 	cases := map[string]string{
 		"hello world":    "'hello%sworld'",