merge: preserve cache guidance source 3173 with measured cost boundaries

package.json

@@ -316,6 +316,7 @@
     "skills/prediction-market-oracle-research/",
     "skills/prediction-market-risk-review/",
     "skills/project-flow-ops/",
+    "skills/prompt-caching-strategy/",
     "skills/prompt-optimizer/",
     "skills/python-patterns/",
     "skills/python-testing/",