fix(ui): report ambiguity on partial process name match (#564)

When multiple processes match a partial `--app` query (e.g. `-a
terminal` matching two `WindowsTerminal` instances) and all have visible
windows, the code silently fell through to title search which then
failed with a misleading *No running app found* error.

Now it throws a clear error listing the matching PIDs, process names,
and window titles — consistent with the exact-name-match path:

```
Multiple processes matching 'terminal' found:
  PID 6816 (WindowsTerminal): ...
  PID 10516 (WindowsTerminal): Administrator: Windows PowerShell
Use --app with a PID or a more specific window title.
```

Co-authored-by: Nikola Metulev <711864+nmetulev@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: nmetulev

src/winapp-CLI/WinApp.Cli/Services/UiSessionService.cs

@@ -355,6 +355,19 @@ private static void RefreshWindowTitle(UiSessionInfo session)
                     LogPartialMatch(app, result);
                     return result;
                 }
+
+                if (withWindow.Length > 1)
+                {
+                    var listing = string.Join("\n  ",
+                        withWindow.Select(p =>
+                        {
+                            try { return $"PID {p.Id} ({p.ProcessName}): \"{p.MainWindowTitle}\""; }
+                            catch { return $"PID {p.Id}"; }
+                        }));
+                    throw new InvalidOperationException(
+                        $"Multiple processes matching '{app}' found:\n  {listing}\n" +
+                        "Use --app with a PID or a more specific window title.");
+                }
             }
         }
         finally