* chore: prefer es-toolkit helpers and lint the mechanical cases
AGENTS.md now names the es-toolkit helpers to reach for instead of hand-written equivalents, and the exceptions: a single clear native call or a measured hot path. The new open-pencil/prefer-es-toolkit rule rejects filter(Boolean) and Set round trips on arrays, the two cases that need no type information, and the existing 45 sites use compact and uniq. tools/ci/policy runs before dependencies are installed, so the rule is off there.
* refactor: deduplicate diagnostic categories with uniq
* fix: keep es-toolkit out of serialized Playwright callbacks
The codemod rewrote a filter(Boolean) inside a page.evaluate callback, which Playwright runs in the page where the compact import does not exist. The spec filters there again, and the rule now skips callbacks passed to evaluate, $eval, $$eval, evaluateHandle, addInitScript and waitForFunction, and filter calls on iterators from values, keys, entries and matchAll, which compact cannot take.
* test: write the prefer-es-toolkit cases like the other rule tests
Short standalone snippets, as in the base64 and JSON rule tests, instead of a declaration prefix on every case and inline object types.