Fix 1Password Connect numeric log levels misclassified in Grafana (#287)

## Summary
- 1Password Connect uses non-standard numeric log levels (`1`=error, `2`=warn, `3`=info, `4`=debug, `5`=trace) per [1Password/connect#44](https://github.com/1Password/connect/issues/44)
- Alloy extracts the `level` JSON field as-is, so info-level health checks get `level="3"` in Loki
- Grafana expects string level labels — numeric values are unrecognized, causing misclassified log severity/coloring
- Adds a `stage.match` + `stage.template` in the Alloy pipeline scoped to `{namespace="1password"}` to normalize numeric levels to standard strings
- Other services are completely unaffected (scoped by namespace, not global)

## Deployment and Testing
- [ ] Sync alloy-k8s from branch: `argocd app set alloy-k8s --revision fix/onepassword-numeric-log-levels && argocd app sync alloy-k8s`
- [ ] Wait ~2 minutes for new logs to flow
- [ ] Verify level labels: `curl -sG "http://localhost:3100/loki/api/v1/label/level/values" --data-urlencode 'query={namespace="1password"}'` should show `"info"` and `"warn"` instead of `"3"` and `"2"`
- [ ] Check Grafana log panel for 1password namespace — logs should no longer appear as errors
- [ ] After merge: `argocd app set alloy-k8s --revision main && argocd app sync alloy-k8s`

Reviewed-on: #287

docs/changelog.d/fix-onepassword-numeric-log-levels.bugfix.md

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+Fix 1Password Connect logs showing as errors in Grafana by normalizing numeric log levels (1-5) to standard strings (error/warn/info/debug/trace) in the Alloy log processing pipeline.