fix: use frappe.db.count instead of get_list for counting records

[badal8381]

Summary

• Replaced frappe.get_list() with count(*) field approach with frappe.db.count() for counting records
• Fixes lead loading issues in the CRM portal

Problem

The CRM portal was failing to load leads due to the way record counts were being fetched. The previous implementation used:
frappe.get_list(doctype, filters=filters, fields="count(*) as total_count")[0].total_count

This approach can be unreliable and may fail in certain edge cases.

Solution

Replaced with the more robust and recommended Frappe API method:
frappe.db.count(doctype, filters=filters)

This change was applied in two locations within crm/api/doc.py:

1. Kanban column count calculation (all_count)
2. Total count for list view (total_count)

Test Plan

• Verify leads load correctly in CRM portal
• Verify Kanban view displays correct counts
• Verify list view pagination works correctly