Decommission JobSync service (#308)

## Summary

- Remove all JobSync infrastructure: ArgoCD app, k8s manifests, container build (nix), Caddy reverse proxy entry, Homepage dashboard entry, service-versions tracking, and all documentation
- Runtime teardown already completed: ArgoCD app cascade-deleted (removes deployment, PVC, service, ingress, external-secret), forge mirror deleted, 1Password item archived, local clone removed

## Motivation

Replacing JobSync with a datasette-based job tracking pipeline driven by mise tasks and a Claude agent frontend. JobSync's Next.js server actions don't expose a useful API for automation.

## Remaining manual steps after merge

- Provision Caddy to remove the stale proxy route: `mise run provision-indri -- --tags caddy`
- Sync Homepage: `argocd app sync homepage`
- Verify namespace cleanup on ringtail: `kubectl get ns jobsync --context=k3s-ringtail` (should be gone)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Reviewed-on: #308

docs/reference/infrastructure/ringtail.md

@@ -70,7 +70,6 @@ Sync order: `1password-connect-ringtail` -> `external-secrets-crds-ringtail` ->
 | [[authentik]] | `authentik` | OIDC identity provider |
 | [[ntfy]] | `ntfy` | Push notification server |
 | [[ollama]] | `ollama` | LLM inference with GPU (RTX 4080) |
-| [[jobsync]] | `jobsync` | Job application tracker |
 | nvidia-device-plugin | `nvidia-device-plugin` | Exposes GPU to pods via CDI + nvidia RuntimeClass |
 
 ### Manual Cluster Registration