Add skill trigger eval harness and improve skill descriptions (#275)

* skill update

* Add skill trigger eval harness, improve skill descriptions, and add trigger evals

- Add eval harness (skills/eval/) based on skill-creator: run_eval.py for
  multi-skill evaluation, run_loop.py for iterative description optimization,
  and eval_lib.py with shared utilities including HTML report generation
- Add trigger evals (5 queries each) for all 37 skills in ./skills
- Improve skill descriptions for better trigger accuracy (b2c-localization,
  b2c-metadata, b2c-forms, b2c-slas-auth-patterns, b2c-content, b2c-ecdn,
  b2c-sites, testing)
- Extract long skill sections to references/ (eCDN security/advanced,
  SLAS passkeys, testing command patterns)
- Create b2c-am skill for Account Manager topic
- Add skills:eval and skills:eval:optimize package.json scripts

Author: clavery

.claude/settings.json

@@ -0,0 +1,5 @@
+{
+  "enabledPlugins": {
+    "skill-creator@claude-plugins-official": true
+  }
+}