Frontend and backend updates to improve activity visibility and multi-server support.
Backend: extend activity summary window to 90 days and add per-day series for the top user (top_user_daily) to the activity summary API.
Frontend:
- Activity tab refactor: rename feed→logs, add pagination, server-side audit log fetching, richer filters, icons, action formatting, details rendering, and improved loading/empty states.
- New ContributionGraph component + styles to visualize daily activity and per-user contributions; graphs injected into ActivityTab.
- Sidebar: separate manual vs auto-expanded state, auto-expand active parent, and persist preset switch locally while persisting to API in background.
- Dashboard: add server selector and remote-server metrics fetching, use remote metrics when a non-local server is selected, adjust polling and refresh semantics, and various UI/icon tweaks.
- Appearance tab: remove inline white-label UI; introduce a dedicated WhiteLabelTab component for custom branding.
Misc: add component and page SCSS files and small README updates describing new features and priority areas.