Add JobSync reference card, observability docs, and RAPIDAPI_KEY plumbing (#289)

## Summary
- Add JobSync service reference card (`docs/reference/services/jobsync.md`) with architecture, secrets, observability, and JSearch API docs
- Add JobSync and Ollama to ringtail's workloads table (both were missing)
- Add JobSync to the reference index
- Wire `RAPIDAPI_KEY` through ExternalSecret and deployment env var for JSearch job search automation
- Document Loki log queries for observability (no metrics endpoint exists)
- Update deploy-jobsync how-to with new env var, observability section, and reference card link

## Deployment and Testing
- [ ] Sign up for RapidAPI JSearch API (free tier: 500 req/month)
- [ ] Add `rapidapi_key` field to "JobSync" 1Password item
- [ ] Merge PR
- [ ] `argocd app sync jobsync` to pick up new env var
- [ ] Verify job search works at https://jobsync.ops.eblu.me/dashboard/automations

Reviewed-on: #289

docs/reference/reference.md

@@ -25,6 +25,7 @@ Individual service reference cards with URLs and configuration details.
 | [[grafana]] | Dashboards & visualization | k8s |
 | [[immich]] | Photo management | k8s |
 | [[jellyfin]] | Media server | indri |
+| [[jobsync]] | Job application tracker | k8s (ringtail) |
 | [[kiwix]] | Offline Wikipedia & ZIM archives | k8s |
 | [[loki]] | Log aggregation | k8s |
 | [[tempo]] | Distributed tracing | k8s |