What type of PR is this?

/kind feature

What this PR does / why we need it:

Fork-only archival validation for the staged agent-sandbox compatibility study.

This PR adapts the current AgentCube baseline from sigs.k8s.io/agent-sandbox v0.1.1 to v0.3.10. Unlike v0.2.1, v0.3.10 requires runtime-aware warm-pool adaptation:

• use public sandboxv1alpha1.SandboxPodNameAnnotation
• wait for SandboxClaim.Status.SandboxStatus.Name and route through the adopted Sandbox
• keep the stored session resource name as the SandboxClaim for delete/GC
• set SandboxTemplate.Spec.NetworkPolicyManagement to Unmanaged
• align codegen with the Kubernetes/client-go version from go.mod
• close the Kubernetes 0.35 lint fallout around fake client deprecations and handler complexity

This is not an upstream review request. It exists to preserve the v0.3.10 checkpoint and trigger fork CI.

Which issue(s) this PR fixes:
Refs volcano-sh#386

Special notes for your reviewer:

• Scope: staged agent-sandbox v0.3.10 compatibility checkpoint.
• Changed files: 16 files, including dependency files, workloadmanager logic/tests, codegen script, generated files, and lint-only test helpers required by Kubernetes 0.35 staticcheck.
• CI result: all fork checks passed on head 142c56e, including build, coverage, e2e-test, golangci-lint, Codegen Check, Python Lint, codespell, and python-sdk-tests.
• Tests:
  • go test ./pkg/workloadmanager -count=1
  • make lint
  • go test ./cmd/workload-manager ./cmd/agentd -count=1
  • go list ./... | grep -v '^github.com/volcano-sh/agentcube/test/e2e$' | xargs go test -count=1
  • go test ./test/e2e -run '^$' -count=1
  • make build-all
  • make gen-check
  • git diff --check
  • git diff --exit-code
• Note: no fresh k3s/k3d runtime e2e was run for this checkpoint. Runtime e2e evidence exists for the later v0.4.6 adaptation path.
• AI assistance: Used Codex to run the staged compatibility experiment, inspect generated diffs, triage fork CI, and prepare this fork-only PR. I reviewed the changes and validation output.

Does this PR introduce a user-facing change?:

NONE