Add `contains`, `startsWith`, `endsWith` string query operators (#1714)

* Initial plan

* Add contains, startsWith, endsWith query operators for partial string matching

Co-authored-by: typicode <5502029+typicode@users.noreply.github.com>

* Delete package-lock.json

* docs: document contains, startsWith, endsWith operators in README

Co-authored-by: typicode <5502029+typicode@users.noreply.github.com>

* test: add numeric-value tests for contains, startsWith, endsWith operators

Co-authored-by: typicode <5502029+typicode@users.noreply.github.com>

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: typicode <5502029+typicode@users.noreply.github.com>
Co-authored-by: typicode <typicode@gmail.com>