[FEATURE] Implement pagination for alerts endpoint to improve performance with large datasets

[ritgit24]

The /api/alerts/ endpoint currently returns all alerts in a single response, which causes severe performance issues when alert volume grows:

• Slow dashboard: Page might take a lot of time to load in case of large payloads which might affect in production
• Frontend freezes: ag-grid table tries to render thousands of rows, causing browser UI to become unresponsive

A solution to the same issue can be implementing server-side pagination on the alerts endpoint with the following characteristics:

Backend API:

• Paginated responses with metadata: [{count, next, previous, results}]
• Configurable page size : default: 25 alerts/page, max: 100 with Query parameters and filter support

Frontend UI:

• Pagination controls: First/Previous/Next/Last buttons
• This will help establish smooth browsing without refetching entire dataset
• This can be integrated seamlessly with existing date range filter