test: make Firefox install output assertion wrap-safe

- Normalize Rich CLI output before asserting the packaged Firefox manifest path.
- Replace split substring checks with the full expected manifest path.
- Keep the warning assertion stable when terminal wrapping inserts line breaks.

tests/test_cli.py

@@ -141,9 +141,9 @@ def test_install_writes_firefox_allowed_extensions(tmp_path):
   ]
   assert "about:debugging#/runtime/this-firefox" in result.output
   assert "npm run package:extension:firefox" in result.output
-  assert "dist/extension-package-firefo" in result.output
-  assert "x/manifest.json" in result.output
-  assert "Do not select extension/manifest.json" in result.output
+  output_unwrapped = result.output.replace("\n", "")
+  assert "dist/extension-package-firefox/manifest.json" in output_unwrapped
+  assert "Do not select extension/manifest.json" in output_unwrapped
   assert "Firefox extension ID" in result.output
 
 def test_install_windows_registers_native_host(tmp_path):