fix(runner): an ambiguous name loses to the coordinates it was built from

Attribute values match by substring, so a selector that named one element
where the candidate was built can name several in the tree it resolves
against, and the lookup sent every one of them to the first match. The host
gates blank an ambiguous tag at enumeration time; this closes the gap between
that moment and the action.

A bare-string target carries no coordinates, so the first match stays the
answer there rather than dropping an authored action.

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

internal/runner/runner.go

@@ -903,8 +903,15 @@ func resolveCoordinates(action verifier.Action, tree *hierarchy.Tree) (int, int,
 		return 0, 0, false
 	}
 	if tree != nil {
-		if element := tree.Find(action.On); element != nil {
-			x, y := element.Bounds.Center()
+		// An ambiguous selector names several elements while the action's own
+		// coordinates name one, so the coordinates win. Attribute values match
+		// by substring, so a selector unique where the candidate was built can
+		// be ambiguous in the tree it resolves against. A bare-string target
+		// carries no coordinates, and there the name is all there is.
+		matches := tree.FindAll(action.On)
+		hasCoordinates := action.X > 0 && action.Y > 0
+		if len(matches) > 0 && (len(matches) == 1 || !hasCoordinates) {
+			x, y := matches[0].Bounds.Center()
 			if x > 0 && y > 0 {
 				return x, y, true
 			}