Ensure ssr branches are included in esm-bundler build

Editor assessment

A reasonable header with a debatable type. The change ensures SSR branches land in the esm-bundler build; if the branches were previously missing due to build misconfiguration, that is arguably a `fix` or `build` matter affecting shipped output, while `refactor` claims no behavioral change and may mislead readers. The subject itself is clear and imperative: 'ensure ssr branches are included in esm-bundler build', specific about both the code path and the bundle target. No scope is used; `(esm-bundler)` would aid changelog grouping in this monorepo. There is no body explaining how inclusion was guaranteed, probably via conditional compilation flags, which is the interesting mechanism. Conforms structurally; a type reconsideration and one line of mechanism would improve it.