Add pre/post lease hooks

[kirkbrauer]

Implement new hook scripts that can be configured in the exporter config to run j commands within a temporary lease environment.

The following environment variables are exposed to hook scripts:

• JUMPSTARTER_HOST - Path to the Unix socket for j CLI access
• JMP_DRIVERS_ALLOW=UNSAFE - Allows all drivers for local access
• LEASE_NAME - The name of the current lease
• CLIENT_NAME - Name of the client that acquired the lease

Example YAML config:

apiVersion: jumpstarter.dev/v1alpha1
kind: ExporterConfig
metadata:
  namespace: default
  name: test-exporter
endpoint: grpc.jumpstarter.100.123.60.47.nip.io:8082
hooks:
  beforeLease:
    script: |
      echo "Starting lease setup for ${CLIENT_NAME}"
      echo "Setting up power management..."
      j power on
      echo "Initializing device connections..."
      echo "Running pre-lease diagnostics..."
      sleep 5
      echo "Pre-lease setup completed successfully!"
    timeout: 120
    onFailure: exit
  afterLease:
    script: |
      echo "Starting lease cleanup for ${CLIENT_NAME}"
      echo "Shutting down power..."
      j power off
      echo "Cleaning up device connections..."
      echo "Running post-lease diagnostics..."
      sleep 5
      echo "Post-lease cleanup completed successfully!"
    timeout: 60
    onFailure: warn
tls:
  ca: ''
  insecure: true
token: abc123
grpcOptions: {}
export:
  power:
    type: "jumpstarter_driver_power.driver.MockPower"
    config: {}

Summary by CodeRabbit

• New Features
  • Exporter status now exposed (STATUS column, CLI "status" option), status streaming, EndSession support, and before/after lease hook lifecycle with timeouts and failure modes; exporter exit codes influence run outcomes.
• Tests
  • Added/updated tests covering hooks, status reporting, rendering, readiness gating, and logging.
• Chores
  • Added typed protobuf/grpc stubs and new public enums/type aliases for exporter status and log sources.

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