Frontend Subscriptions list: Add empty state when no data

[aji70]

Description (Frontend)

Optional locale switch.

Optional locale switch.

Frontend area Subscriptions list. Add empty state when no data. Update frontend/src/ as needed.

Tasks

• Implement the change in the relevant code paths
• Wire or persist state where the feature touches runtime behavior
• Add tests (unit, integration, and/or contract/UI as appropriate)

Additional Requirements

• Handle stale, disconnected, or invalid states gracefully where applicable
• Follow existing patterns in this repository (linting, modules, security)

Acceptance Criteria

• i18n groundwork (extract strings) is done and verifiable (CI and/or a short manual checklist)
• No regressions in closely related user or API flows