feat: harness VM stack (runner, measure-db, blackbox, Alloy, k6) and the 12 scenarios

Experiment design 5 and 7 for the harness VM (10.20.0.11): vm/harness/apply.sh pulls the secrets from Secret Manager,
compose runs runner:de076a7, measure-db, blackbox, Alloy (probe_success -> Mimir) and k6 under the campaign profile.
Scenario files C-K1..X-M2 are loaded by the runner. Harness ClusterRole gains replicasets get/list for rollout undo.

vm/harness/scenarios/C-G2.yaml

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+# design 7 C-G2: grey zone, container. StressChaos memory on api pods; latency rises, intermittent 5xx. Correct: k8s.rollout_restart after approval.
+id: C-G2
+path: gray
+asset: container
+expected_layer: 2
+ground_truth_label: memory_pressure_api
+ground_truth_action: k8s.rollout_restart
+description: StressChaos memory workers 2 size 80%, app=api, duration 10m
+notes:
+  open_item: "design 11.3: whether the stress re-attaches to the restarted pods for the remaining duration"
+inject:
+  method: chaos
+  manifest: |
+    apiVersion: chaos-mesh.org/v1alpha1
+    kind: StressChaos
+    metadata:
+      namespace: chaos-mesh
+    spec:
+      mode: all
+      selector:
+        namespaces: [demo]
+        labelSelectors:
+          app: api
+      stressors:
+        memory:
+          workers: 2
+          size: "80%"
+      duration: "10m"
+revert:
+  method: chaos_delete