#22808: test(ui): split baseline browser-test fixes from webchat feature

## Summary Split out baseline UI test fixes that are not specific to the multi-chat feature. ## Changes - `ui/src/ui/test-helpers/app-mount.ts` - ensure app registration side-effects are loaded in browser tests: - `import "../app.ts";` - `import type { OpenClawApp } from "../app.ts";` - `ui/src/ui/navigation.test.ts` - align expected tab-group labels with current `TAB_GROUPS` values (lowercase labels). ## Why These failures reproduce on `main` and are unrelated to the webchat multi-session feature itself. ## Validation - `pnpm -C ui test src/ui/navigation.browser.test.ts src/ui/navigation.test.ts` - Result: **2 files passed, 40 tests passed** --- **AI-generated contribution:** This PR was primarily generated with AI assistance and then validated with local tests. <!-- greptile_comment --> <h3>Greptile Summary</h3> Fixes two pre-existing test failures on `main`: - **`navigation.test.ts`**: Updates `TAB_GROUPS` label expectations from capitalized (`"Chat"`, `"Control"`, etc.) to lowercase (`"chat"`, `"control"`, etc.), matching the actual values changed in commit `4b17ce7` (i18n feature) where labels were lowercased but tests were not updated. - **`app-mount.ts`**: Splits the `OpenClawApp` import into a bare side-effect import (`import "../app.ts"`) to ensure the `@customElement("openclaw-app")` decorator registers the custom element, plus a `type`-only import for the type cast. This makes the side-effect dependency explicit rather than relying on a value import to trigger module evaluation. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge — it only fixes test expectations and import style with no production code changes. - Both changes are minimal, test-only fixes that align test expectations with existing source code. The TAB_GROUPS label change is verified against the actual `navigation.ts` source. The import refactor in `app-mount.ts` correctly separates the side-effect import from the type-only import, which is a best practice for custom element registration. No production code is modified. - No files require special attention. _{Last reviewed commit: a57e2ec} <!-- greptile_other_comments_section --> _{(3/5) Reply to the agent's comments like "Can you suggest a fix for this @greptileai?" or ask follow-up questions!} <!-- /greptile_comment -->