fix(bootstrap): detect low inotify limits before gateway startup

[RPirruccio]

Summary

Detect low fs.inotify.max_user_instances before k3s starts and surface it in openshell doctor check. On hosts running existing container workloads, the default limit (128) can be exhausted, causing containerd's CRI plugin to fail with "too many open files" when creating its fsnotify watcher. The RuntimeService never registers, which surfaces as the "K8s namespace not ready" timeout.

The fix is warn-only. It doesn't change any kernel params, just tells you what's wrong and how to fix it yourself.

Related Issue

Related to #552

Changes

• cluster-entrypoint.sh: check inotify limit before starting k3s, warn if below 256 with exact fix command
• doctor_check() in run.rs: add inotify instances check (Linux only) after existing Docker check

Testing

Tested on Ubuntu 24.04, Docker 29.0.4, kernel 6.17.0 with existing k3s cluster on host. Root cause confirmed via docker exec:

failed to load plugin: failed to create CRI service: failed to create cni conf monitor:
failed to create fsnotify watcher: too many open files

sudo sysctl -w fs.inotify.max_user_instances=512 resolved immediately.

• mise run pre-commit passes
• Unit tests added/updated
• E2E tests added/updated (if applicable)

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)
• Architecture docs updated (if applicable)

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[RPirruccio]

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