Add merged-menu overview tab with configurable providers

[ratulsarna]

Summary

This PR adds a merged-menu Overview tab and wires it through settings, menu rendering, and reconciliation.

• Add an Overview tab to the merged provider switcher when merged mode is on, multiple providers are enabled, and overview has visible providers.
• Render overview content by stacking provider sections (up to the configured cap) using existing menu-card rendering paths, and allow selecting a provider detail view from overview rows.
• Add display settings for Overview tab providers with configurable provider selection (cap-enforced, empty selection supported).
• Reconcile persisted overview selection against active providers, including order-insensitive matching for edited contexts and behavior for zero/limited active providers.
• Remove provider-context actions from overview mode where they don’t map correctly to multi-provider context.
• Ensure smart menu updates rebuild the switcher when Overview availability toggles, so the switcher never gets stuck with stale Overview visibility.
• Centralize the overview provider cap constant and align usage across menu/settings/test logic.

Validation

• swift test --filter StatusMenuTests
• pnpm check
• ./Scripts/compile_and_run.sh