#187 AF-293: make client release bundle deployable

[Anonymous]

Originally created by: AnaniyaT

Make the v0.17.0 client bundle deployable: the helmfile requires monitoring inputs the generated .env.deploy never carried, and the rebranded agent-barn/* registry path is not yet allowed by the tenant ACL. Supersedes [#186] (closed by the branch rename).

What's included

• helmfile.yaml.gotmpl — installed: on the monitoring release via MONITORING_ENABLED (default true). Existing deploys are unchanged.
• .env.deploy.spec — add MONITORING_ENABLED, GRAFANA_HOST, GRAFANA_ADMIN_PASSWORD, SLACK_ALERTS_WEBHOOK_URL with placeholders and guidance.
• .github/workflows/client-release.yml, release-bundle.yml — image_prefix input (default agent-barn). Passing agent-farm publishes to the path existing client credentials already allow; the bundle's REGISTRY_PREFIX follows the same input.

Required repo config
none

Notes

• No app code or chart files changed, so no chart version bump.
• Registry ACL extension for agent-barn/* is an infra change in k3s-hetzner-cluster-infra, not part of this PR.
• Targets main because the change is needed for a client release cut from main.

Testing

• helmfile -f helmfile.yaml.gotmpl list with MONITORING_ENABLED unset, true, false: monitoring shows INSTALLED=true / true / false, all other releases unchanged.
• Workflow files parsed as YAML.