feat: Analytics panel && Improve analytics charts readability and zone/source UX polish

[666mxvbee]

This PR adds the first full version of the Analytics section to the admin panel.

Implemented:

• Added /analytics route and sidebar navigation entry.
• Added frontend analytics API client for /admin/analytics/* contracts.
• Added analytics access logic for admins and partner users.
• Built the main analytics dashboard with:
  • period, zone, camera, granularity filters;
  • auto-refresh;
  • KPI cards;
  • Yandex map with cameras and zones;
  • occupancy history chart;
  • occupancy forecast chart;
  • observations rate chart;
  • model confidence chart;
  • detector health table.
• Added zone analytics detail view.
• Added camera analytics detail view with snapshots, charts, zone health, and recent detections.
• Added detection run detail view with raw/annotated image comparison.
• Added detection quality feedback form.
• Added admin-only feedback history block.
• Added VITE_ANALYTICS_STALE_MINUTES to .env.example.
• improved analytics charts readability with axis labels, grid lines, tick labels, and point aggregation
• made analytics granularity actually affect chart rendering for legacy /occupancy and /forecasts data
• added interactive chart tooltips with hover/click behavior for line charts
• removed zone creation flow from the Zones page so zones are created only through a specific camera
• cleaned up zone UI labels and removed unnecessary Partner ID controls
• added horizontal scrolling to the Sources table
• fixed camera filter submit on Enter
• fixed active zone handles so they remain draggable above overlapping polygons