feat: add Kubernetes topology tree APIs

[Cynthia-0203]

What this PR does / Why we need it:

This PR adds backend APIs for Kubernetes environment topology tree.

It allows the environment page to visualize Kubernetes resources as a topology graph, including workloads, pods, services, ingresses, config maps, secrets, PVCs, and their relationships. It also exposes sync status, health status, node-level actions, YAML diff, and service sync capabilities, so users can better understand runtime state and configuration drift in Kubernetes YAML environments.

What is changed and how it works?

• Added topology routes under environment APIs:
  • GET /environments/:name/topology
  • GET /environments/:name/topology/node
  • GET /environments/:name/topology/diff
  • POST /environments/:name/topology/sync

Does this PR introduce a user-facing change?

• API change
• database schema change
• upgrade assistant change
• change in non-functional attributes such as efficiency or availability
• fix of a previous issue

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This change is