chore(server): pass app_config only to provider factory and providers

[Pangjiping]

Summary

• create_workload_provider() now takes (provider_type, k8s_client, app_config)
  instead of separate k8s_config, agent_sandbox_config, ingress_config
• BatchSandboxProvider and AgentSandboxProvider init take (k8s_client,
  app_config) and read kubernetes/agent_sandbox/ingress from app_config
• Keep optional informer_factory kwarg for tests
• Update KubernetesSandboxService call site and all provider tests to use
  app_config fixtures/helpers

Testing

• Not run (explain why)
• Unit tests
• Integration tests
• e2e / manual verification

Breaking Changes

• None
• Yes (describe impact and migration path)

Checklist

• Linked Issue or clearly described motivation
• Added/updated docs (if needed)
• Added/updated tests (if needed)
• Security impact considered
• Backward compatibility considered

[jwx0925]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Can't wait for the next one!

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