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/performing-container-security-scanning-with-trivy/SKILL.md

@@ -1,10 +1,13 @@
 ---
 name: performing-container-security-scanning-with-trivy
-description: Scan container images, filesystems, Git repositories, and Kubernetes manifests
-  for OS and language-dependency vulnerabilities, IaC misconfigurations, exposed secrets,
-  and license issues using Aqua Security's Trivy, generating CycloneDX/SPDX SBOMs. Use
-  when integrating vulnerability scanning into CI/CD pipelines, deploying the Trivy
-  Kubernetes operator, or triaging scan results for security operations.
+description: >-
+  Runs Trivy across every target type it supports - container images, filesystems, Git
+  repositories, and Kubernetes clusters - for OS and dependency vulnerabilities, IaC
+  misconfiguration, exposed secrets, and licences, generating CycloneDX or SPDX SBOMs. Use
+  when integrating Trivy into CI/CD, deploying the Trivy Kubernetes operator, scanning
+  non-image targets, or triaging results at scale. Keywords: Trivy, trivy k8s, operator, SBOM,
+  CycloneDX, SPDX, misconfig, secret scanning. Do not use for a single Docker image scan - use
+  scanning-docker-images-with-trivy.
 domain: cybersecurity
 subdomain: container-security
 tags: