Feature/admin dashboard revision

[Polliog]

This pull request delivers a comprehensive redesign and upgrade of the admin dashboard, focusing on platform observability, monitoring, and consistency improvements. It introduces new backend endpoints for platform statistics, fixes several frontend/backend mismatches, and enhances admin panel usability and reliability.

Admin Dashboard Redesign & Observability:

• Complete overhaul of the admin dashboard, adding health status cards, platform activity charts, stat cards, and top organizations/projects tables for improved platform-level observability.
• Added five new backend endpoints in routes.ts for platform timeline, active issues, compression stats, continuous aggregates health, and slow/active queries, enabling richer dashboard features.
• Implemented corresponding service methods in service.ts for platform timeline aggregation, active issues summary, slow query monitoring, and stats interfaces.
• Added frontend API interfaces and methods for new dashboard endpoints, allowing seamless integration and data fetching for new dashboard widgets. [1] [2]

Monitoring & Diagnostics Improvements:

• Fixed continuous aggregates health reporting ("Refresh: unknown") by querying the correct column for schedule_interval.
• Introduced slow queries monitoring using both live and historical data from PostgreSQL, including color-coded durations and support for pg_stat_statements extension.

Admin Panel Consistency & Bug Fixes:

• Resolved frontend/backend type mismatches in health stats: aligned status values, added missing pool property, and supported 'not_configured' for Redis. [1] [2]
• Improved admin panel reliability: added admin guards to key pages, replaced unsafe delete patterns with proper confirmation modals, standardized modals, and fixed navigation and reactivity issues.

These changes collectively enhance platform monitoring, admin experience, and operational reliability.