Drop support for yarn@1, set packageManager field in package.json (pnpm 10.x, npm 11.x) #915

Job	Run time
Lint JS	17s
Tests (addon-location)	1m 13s
Slow tests: defaults with npm	2m 38s
Tests (test-app-location)	1m 14s
Slow tests: defaults with pnpm	55s
Tests (addon-only)	28s
Slow tests: typescript with npm	2m 41s
Tests (monorepo with npm)	1m 41s
Slow tests: typescript with yarn	14s
Tests (monorepo with pnpm)	47s
Slow tests: typescript with pnpm	1m 31s
Tests (rollup-build)	1m 7s
Tests (declarations-configuration)	32s
Tests: Type Check	11s
	15m 29s

Provide feedback