Rewrite service readiness check and remove orchestration service

[hugosantos]

Summary

Replace port-forwarding based service readiness checks with a simpler, more reliable one-shot pod approach. This eliminates the orchestration service RPC entirely and makes readiness checks work consistently for both in-cluster and remote Kubernetes clusters.

Key Changes

1. Service Readiness Check Rewrite

Before:

• Used RawDialServer() with port-forwarding
• Required in-cluster access via *.svc.cluster.local DNS
• Complex async error handling
• Bash-specific /dev/tcp device

After:

• Deploys one-shot pod with shell script inside cluster
• Uses nc (netcat) for TCP connectivity tests
• Simple pass/fail via pod exit code
• POSIX-compliant shell script for busybox compatibility
• Works for both remote and in-cluster deployments

2. Orchestration Service Removal

Deleted:

• orchestration/service/ package (~400 lines)
• orchestration/proto/ package (~800 lines)
• CallAreServicesReady() RPC function

The AreServicesReady RPC was the only remaining orchestration service endpoint. Since we now handle readiness checks directly without RPC, the entire service package is no longer needed.

3. Orchestrator Deployment Changes

• Set UseOrchestrator = false (was true)
• Made orchestrator preparation conditional on flag
• Orchestrator still available via --use_orchestrator flag for runtime config controllers

4. Security Improvements

• Uses Chainguard busybox image (cgr.dev/chainguard/busybox:latest)
• Minimal, secure base image with no CVEs
• Runs as uid 65532 (nonroot)
• Read-only root filesystem enforced

Implementation Details

The new readiness checker:

1. Lists K8s services matching the deployable
2. Generates a POSIX-compliant shell script that tests each TCP port
3. Deploys a one-shot pod running the script inside the cluster
4. Script uses nc -z to test TCP connectivity with retry logic (60 attempts × 500ms = 30s)
5. Returns success if pod exits with code 0, failure otherwise
6. Pod is automatically cleaned up via defer

Testing

• ✅ All Go tests pass (go test ./...)
• ✅ Full codebase builds (go build ./...)
• ✅ nsdev prepare local completes without deploying orchestrator
• ✅ nsdev test runs successfully (service readiness check executes)

Benefits

• Simpler: Direct K8s API calls, no RPC layer
• More reliable: Actual TCP dial inside cluster vs async port-forward errors
• Works remotely: Uses K8s API to deploy/watch pod
• More secure: Chainguard minimal image, CVE-free
• Cleaner codebase: -585 lines of code (mostly dead orchestration service)

Breaking Changes

None. The orchestration service RPC was already unused - this just removes the dead code.

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