fix(sglang): route resolved ServerArgs updates through override

[furionw]

Summary

• add one compatibility helper for post-resolution SGLang ServerArgs updates
• use ServerArgs.override on frozen newer SGLang versions
• retain direct assignment for older SGLang and SimpleNamespace stubs
• route all current Dynamo post-resolution mutations through the helper

Stack

Base: PR1, qiwa/k3-native-frontend

PR4 depends on this PR.

Validation

• pre-commit run --all-files
• Python bytecode compilation
• unit coverage for modern override and legacy fallback paths

[datadog-official]

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 14.77% (-27.22%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: b69d6f7 | Docs | Datadog PR Page | Give us feedback!}