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-container-network-policies-with-calico/SKILL.md

@@ -1,10 +1,14 @@
 ---
 name: implementing-container-network-policies-with-calico
-description: Enforces Kubernetes network segmentation by creating and auditing Calico
-  NetworkPolicy and GlobalNetworkPolicy resources via calicoctl and the Kubernetes
-  API, controlling pod-to-pod traffic, namespace isolation, egress restrictions, and
-  DNS-based rules. Use when implementing zero-trust microsegmentation in a Calico-CNI
-  cluster or hardening pod-to-pod and egress traffic controls.
+description: >-
+  Uses Calico's own policy CRDs beyond the upstream Kubernetes API - GlobalNetworkPolicy,
+  HostEndpoint, NetworkSet, policy tiers, and DNS-based egress rules - applied and audited
+  with calicoctl. Use when a policy must span namespaces or protect the host itself, when
+  egress has to be expressed by domain name, or when ordering policies into tiers. Keywords:
+  calicoctl, GlobalNetworkPolicy, HostEndpoint, NetworkSet, tier, DNS egress, order. Do not
+  use for portable upstream NetworkPolicy - use implementing-network-policies-for-kubernetes;
+  for installing Calico and writing standard policy with it use
+  implementing-kubernetes-network-policy-with-calico.
 domain: cybersecurity
 subdomain: container-security
 tags: