feat: Implement pagination logic on the dashboard (#163)

[Dev1822]

Description

This PR resolves #163 by implementing proper Next/Previous pagination in the frontend dashboard.

Previously, the dashboard.html used a "Load More" strategy that continuously appended newly fetched jobs and contacts to the DOM. Over time, rendering thousands of elements simultaneously caused severe browser lag and performance issues.

Changes Made

• Refactored loadJobs & loadContacts: Replaced the "Load More" appending behavior with strict page replacement (state.jobs and state.contacts now only store the items for the current page).
• Added Pagination Controls: Introduced "Previous" and "Next" buttons at the bottom of the Jobs grid and the Contacts table.
• Added Pagination Counters: Added a dynamic X-Y of Total indicator to clearly show the user their current offset context within the entire dataset.
• Backend Verification: Leveraged the existing limit and offset query parameters powered by asyncpg in the API gateway.

Testing Instructions

1. Load the dashboard and verify that only 50 jobs/contacts are rendered on the initial load.
2. Click the "Next" button and verify that the view cleanly replaces the previous items with the new page.
3. Verify that the "X-Y of Total" counter accurately reflects your current position.
4. Verify that "Previous" is disabled on the first page and "Next" is disabled on the final page.

[vercel]

@Dev1822 is attempting to deploy a commit to the Vaibhav Sharma's projects Team on Vercel.

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[Dev1822]

@sharmavaibhav31 , kindly suggest me any changes if needed for this pr. If not kindly merge this pr with gssoc and elusoc labels.