Draft: pin patched hl2sdk for CS2 2000872 native rebuild

[tomastaker]

Draft PR for testing the CS2 2000872 update with the SDK changes from alliedmodders/hl2sdk#396.

I am marking this as draft because the final version should not keep pointing at my fork forever. Once alliedmodders/hl2sdk#396 is merged, this submodule should point back to alliedmodders/hl2sdk and the merged commit.

Why I opened this anyway: rebuilding CounterStrikeSharp v1.0.370 against the patched SDK fixed the native load failure on my live Linux CS2 server.

Before rebuilding, the native CSS binary still referenced old symbols like:

• g_bUpdateStringTokenDatabase
• RegisterStringToken

After rebuilding against the patched SDK, those imports were gone.

What I tested:

• rebuilt CounterStrikeSharp v1.0.370 native Linux binary against this SDK commit
• deployed it together with a Metamod build made against the same SDK
• restarted the CS2 container cleanly after deploy

What I saw after restart:

• Metamod loaded normally: [META] Loaded 1 plugin
• CSS started: CounterStrikeSharp.API Loaded Successfully
• CSS hooks were added
• my CSS plugin started and exposed its HTTP endpoint
• plugin health returned status=ok and nativeAuthAvailable=true
• server state returned loggedOnToSteam=true, vacSecure=true, mapTimelimitMinutes=60, mapTimeLeftSource=mp_timelimit

There is still a separate issue: CSS logs missing gamedata signatures for:

• Host_Say
• CEntityInstance_AcceptInput
• CBaseEntity_TakeDamageOld

Those did not block startup or the plugin flow I tested, but they probably still need to be updated before this is fully clean.