Add Prometheus: server only, vendored official chart

Vendored prometheus-community/prometheus 29.27.1 the same way
Contour/ArgoCD/Vault/Gitea/Harbor/Jenkins already are here — a thin
Chart.yaml dependency plus a committed .tgz — rather than hand-written
like postgresql, which has no official chart to vendor.

Server only: alertmanager, kube-state-metrics, prometheus-node-exporter
and prometheus-pushgateway are all enabled by default in this chart and
all disabled here. None are needed for what actually consumes this —
toolshed's per-app CPU/memory metrics read straight from the chart's
built-in kubernetes-nodes-cadvisor scrape job (kubelet's own cAdvisor
endpoint) — and each is its own pod on a node that was already at its
8GB ceiling before this.

Trimmed for the same ceiling: 3Gi PVC on local-path (not the chart's
8Gi default), 7-day retention (not 15), resources capped at 512Mi.

nameOverride pinned to exactly "prometheus" matters more here than for
any other component pinning it: the chart's server Service renders as
"<release-name>-server", so this is what makes it "prometheus-server"
— the exact hostname toolshed's PROMETHEUS_URL was already seeded to
point at, before this existed, so the connection is already correct
the day this deploys.

Verified with `helm template` against the real chart and these values:
server-only object set (ClusterRole, ClusterRoleBinding, ConfigMap,
Deployment, PVC, Service, ServiceAccount — nothing from the four
disabled subcharts), and the rendered PVC/retention/resources/Service
name all match what's written above.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Wajog7nELA3i8JWTjxYGHF

helm-templates/prometheus/Chart.lock

@@ -0,0 +1,6 @@
+dependencies:
+- name: prometheus
+  repository: https://prometheus-community.github.io/helm-charts
+  version: 29.27.1
+digest: sha256:1cd0daed07160b46100e5cccade430dadcd2f9a3974bd3667a09787c603a6ad0
+generated: "2026-09-06T07:25:57.847789+05:30"

helm-templates/prometheus/Chart.yaml

@@ -0,0 +1,10 @@
+apiVersion: v2
+name: prometheus
+version: 1.0.0
+dependencies:
+  - name: prometheus
+    # Pinned to the latest stable at the time this was vendored (2026-09).
+    # Bump deliberately later, with a changelog read first, same as any
+    # other chart bump in this repo.
+    version: 29.27.1
+    repository: https://prometheus-community.github.io/helm-charts