ci: Check for stable lockfile

[mydea]

It keeps happening that we have an out-of-date yarn.lock file, this should hopefully lint against this for the future 🤔

Failing here: https://github.com/getsentry/sentry-javascript/actions/runs/17545403486/job/49825686877?pr=17552

[github-actions]

node-overhead report 🧳

Note: This is a synthetic benchmark with a minimal express app and does not necessarily reflect the real-world performance impact in an application.

Scenario	Requests/s	% of Baseline	Prev. Requests/s	Change %
GET Baseline	9,167	-	9,407	-3%
GET With Sentry	1,330	15%	1,346	-1%
GET With Sentry (error only)	5,950	65%	5,889	+1%
POST Baseline	1,207	-	1,195	+1%
POST With Sentry	486	40%	538	-10%
POST With Sentry (error only)	1,067	88%	1,059	+1%
MYSQL Baseline	3,328	-	3,339	-0%
MYSQL With Sentry	465	14%	480	-3%
MYSQL With Sentry (error only)	2,730	82%	2,735	-0%

View base workflow run

[Lms24]

Nice, thanks!