[nfebe]

Add plugin-provided Settings tabs. Tabs appear only when the matching plugin UI is installed.

[sourceant]

Code Review Summary

Settings tabs are now addressable through the ?tab= query parameter, with unknown or unavailable keys falling back to the account tab, and selecting a tab rewrites the query. Plugin descriptors can declare a settings.tabs entry whose body is the layer-registered component; such tabs are hidden until that component exists and are ordered by the descriptor's order value. The theme also mirrors its state into a data-theme attribute, and icon resolution moved into a shared utility.

🚀 Key Improvements

• Settings tabs become linkable and bookmarkable via ?tab= with a safe account fallback.
• Plugin tabs only appear once their layer registers a component, avoiding broken or empty tabs.
• Icon lookup is shared through utils/integrationIcon.ts instead of duplicated in components.

📉 Regressions

• Selecting a tab calls router.replace with a query object containing only tab, dropping any other query parameters on /settings.

💡 Minor Suggestions

• Review coverage is incomplete. Inspect the execution details before approving.

[sourceant]

Review complete. See the overview comment for a summary.