chore: migrate to Yarn v4

[erickzhao]

Closes #195
Closes #193

This rolls up the Yarn v4 upgrade into #199 (see target branch for this PR) since a Probot migration is required for updating the lockfile anyways.

[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	husky@​9.1.6 ⏵ 9.1.7
	@​vitest/​coverage-v8@​3.0.5 ⏵ 3.2.4			+1	+1
	vitest@​3.0.5 ⏵ 3.2.4				+1
	@​types/​node@​22.9.0 ⏵ 22.19.1	+1		+1	+2
	semver@​7.6.3 ⏵ 7.7.3	+1		+1
	prettier@​3.3.3 ⏵ 3.6.2	+1
	typescript@​5.8.3 ⏵ 5.9.3	+1		+1
	@​sentry/​node@​7.119.2 ⏵ 7.120.4
	lint-staged@​15.2.10 ⏵ 15.5.2			+1	+1

View full report

[socket-security]

All alerts resolved. Learn more about Socket for GitHub.

This PR previously contained dependency changes with security issues that have been resolved, removed, or ignored.

Ignoring alerts on:

• safer-buffer@2.1.2

View full report

[erickzhao]

@SocketSecurity ignore npm/safer-buffer@2.1.2