feat(agent): add Kubernetes readiness and liveness probes

[majiayu000]

Summary

This PR fixes #2311

Adds Kubernetes readiness and liveness probes to the deepflow-agent, following standard K8s patterns.

Changes

• Add /v1/ready/ endpoint to integration collector for readiness probe
• Add /v1/health/ endpoint to integration collector for liveness probe
• Configure readiness and liveness probes in DaemonSet YAML on port 38086

Implementation Details

• Readiness probe: /v1/ready/ returns 200 with {"status":"ready"} when the integration collector HTTP server is ready to accept traffic
• Liveness probe: /v1/health/ returns 200 with {"status":"healthy"} when the server is running
• Both probes use the integration collector's HTTP server on port 38086 (the default external agent HTTP proxy port)

Probe Configuration

readinessProbe:
  httpGet:
    path: /v1/ready/
    port: 38086
  initialDelaySeconds: 5
  periodSeconds: 10
  timeoutSeconds: 5
  failureThreshold: 3

livenessProbe:
  httpGet:
    path: /v1/health/
    port: 38086
  initialDelaySeconds: 15
  periodSeconds: 20
  timeoutSeconds: 5
  failureThreshold: 3

Test plan

• Deploy the agent as a DaemonSet and verify probes work correctly
• Verify readiness probe passes when agent is ready
• Verify liveness probe passes when agent is healthy
• Verify pod restarts if liveness probe fails

🤖 Generated with Claude Code

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