ci: Update actions for queue merge validation (#11114)

## Summary

PR merge queue was enabled but actions were not updated to trigger on
`merge_group`:

https://docs.github.com/en/repositories/configuring-branches-and-merges-in-your-repository/configuring-pull-request-merges/managing-a-merge-queue#triggering-merge-group-checks-with-github-actions

## Changes

- **What**: 
- `.github/actions/lint-format-verify/action.yml` extrated shared Verify
lint and format steps
- `.github/workflows/ci-lint-format.yaml` updated to use shared
composite action
- `.github/workflows/ci-lint-format-queue.yaml` new action that triggers
on merge_group to validate format
- `.github/workflows/ci-tests-e2e.yaml` triggers on merge_group
- `.github/workflows/ci-tests-unit.yaml` triggers on merge_group

## Review Focus

<!-- Critical design decisions or edge cases that need attention -->

<!-- If this PR fixes an issue, uncomment and update the line below -->
<!-- Fixes #ISSUE_NUMBER -->

## Screenshots (if applicable)

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┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-11114-ci-Update-actions-for-queue-merge-validation-33e6d73d3650815f8c88f40736b513ec)
by [Unito](https://www.unito.io)

.github/actions/lint-format-verify/action.yml

@@ -0,0 +1,31 @@
+name: 'Lint and format verify'
+description: >
+  Runs the lint/format/knip verification suite plus a conditional
+  browser-tests typecheck. Shared by ci-lint-format.yaml (PR) and
+  ci-lint-format-queue.yaml (merge queue) so both paths run the exact
+  same checks. The caller is responsible for checkout and frontend setup
+  before invoking this action.
+
+runs:
+  using: composite
+  steps:
+    - name: Detect browser_tests changes
+      id: changed-paths
+      uses: dorny/paths-filter@de90cc6fb38fc0963ad72b210f1f284cd68cea36 # v3.0.2
+      with:
+        filters: |
+          browser_tests:
+            - 'browser_tests/**'
+
+    - name: Verify lint and format
+      shell: bash
+      run: |
+        pnpm lint
+        pnpm stylelint
+        pnpm format:check
+        pnpm knip
+
+    - name: Typecheck browser tests
+      if: steps.changed-paths.outputs.browser_tests == 'true'
+      shell: bash
+      run: pnpm typecheck:browser