docs(skills): rewrite container-security descriptions to a uniform standard

All 33 container-security skills now carry what it does, an explicit
"Use when" trigger, keywords, and a negative trigger naming the nearest
neighbour. Six collision clusters resolved by differentiating scope
rather than merging, so no skill is removed:

- kube-bench: running the tool vs interpreting findings into an audit
- Calico: portable upstream NetworkPolicy vs Calico-as-CNI vs Calico-only
  CRDs (GlobalNetworkPolicy, HostEndpoint, DNS egress)
- Falco: deploying and operating it vs authoring escape rules
- container escape: tool-agnostic runtime signals vs Falco rule syntax vs
  static posture audit vs offensive breakout
- Trivy: all-target platform and operator vs single-image scan
- Docker: images and Dockerfiles vs daemon.json vs the CIS audit script

Also replaces the templated "When to Use" boilerplate in these files,
including bullets that only restated the skill's own name.

Worst pair (Pod Security Standards vs Pod Security Admission) drops from
0.77 cosine to below the 0.45 threshold. Repo-wide: colliding pairs
60 -> 56, skills involved 105 -> 94.

skills/implementing-network-policies-for-kubernetes/SKILL.md

@@ -1,10 +1,13 @@
 ---
 name: implementing-network-policies-for-kubernetes
-description: Writes Kubernetes NetworkPolicy YAML (default-deny-all, DNS egress, namespace/pod
-  selector rules) enforced via CNI plugins like Calico or Cilium to control ingress
-  and egress traffic between pods, namespaces, and external endpoints. Use when
-  implementing zero-trust microsegmentation inside a Kubernetes cluster to prevent
-  lateral movement between workloads or namespaces.
+description: >-
+  Writes portable upstream Kubernetes NetworkPolicy YAML - default-deny-all, DNS egress,
+  namespace and pod selector rules - that works on any conformant CNI such as Calico or
+  Cilium. Use when segmentation must stay CNI-portable, introducing a default-deny posture, or
+  restricting east-west traffic between pods and namespaces without depending on a vendor CRD.
+  Keywords: NetworkPolicy, default deny, podSelector, namespaceSelector, ingress, egress, CNI
+  portable. Do not use for Calico-specific resources - use
+  implementing-kubernetes-network-policy-with-calico.
 domain: cybersecurity
 subdomain: container-security
 tags: