servers: cstrike: add cstrike server

[MaNthegax]

No description provided.

[github-actions]

Server list PR validation

Probed 1 new entry.

Gamedir	Address	Claimed	Responder	Host	Notes
cstrike	131.196.199.248:27015	48 (GoldSrc)	48 (GoldSrc)	.:: ZS.TEAM ::. ZOMBIE PLAGUE UMBRELLA [VIP-FREE] @ZSTEAM.SITE	✅ protocol match.

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_{Probes can be flaky on the first try; the nightly publish workflow re-probes with a 48 h grace window, so a single ❌ here is not necessarily fatal. Re-push to re-run.}