planning: add issue add-model-id-to-test-results-schema to 2.1

add fully-qualified model ID to test-results schema for cache invalidation

Author: cowwoc

.cat/issues/v2/v2.1/add-model-id-to-test-results-schema/index.json

@@ -0,0 +1,3 @@
+{
+  "status" : "open"
+}

.cat/issues/v2/v2.1/add-model-id-to-test-results-schema/plan.md

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+# Plan
+
+## Goal
+
+Add fully-qualified model ID to test-results schema so cached SPRT results are invalidated when the
+model changes.
+
+## Pre-conditions
+
+(none)
+
+## Post-conditions
+
+- [ ] Both skills results.json and rules test-results.json schemas include a fully-qualified model ID field (e.g., claude-haiku-4-5-20251001)
+- [ ] Tests passing for schema validation
+- [ ] Mismatch between stored model ID and current model ID is detectable and triggers re-validation
+- [ ] No regressions in existing test infrastructure
+- [ ] E2E verification: store a test result with model ID, change the model, verify the cached result is flagged as stale