Added search to new case contact datatable view

[jamesh38]

What github issue is this PR for, if any?

Resolves #6504

What changed, and why?

Added server-side search to the new case contacts table for better performance with large datasets.

Backend:

• Created CaseContactDatatable to handle server-side DataTables processing with search across creator name, creator email, case number, notes, and contact types
• Added datatable? permission in CaseContactPolicy for admins, supervisors, and volunteers
• Used ActiveRecord + .to_sql pattern instead of raw SQL for maintainability

Frontend:

• Updated dashboard.js to configure DataTables with server-side processing
• Set up all 11 column renderers (icons, links, duration formatting, draft badges)

Why? Loading all case contacts client-side would get slow with lots of data. Server-side processing lets the database handle filtering and pagination, only returning one page at a time.

How is this tested?

rspec (46 tests):

• spec/datatables/case_contact_datatable_spec.rb - 35 tests for data structure, search, ordering, pagination, sanitization
• spec/policies/case_contact_policy_spec.rb - 3 tests for permissions
• spec/requests/case_contacts/case_contacts_new_design_spec.rb - 8 tests for endpoint authorization and scoped data

jest (48 tests):

• app/javascript/__tests__/dashboard.test.js - tests for DataTable config, AJAX setup, all column renderers

# run tests
bin/rspec spec/datatables/case_contact_datatable_spec.rb
npm test -- dashboard.test.js

[jamesh38]

Thanks for triggering the review @compwron addressed final two issues and fixed tests

[compwron]

:)