chore(memory): L0 line-1 convention — all files start with L0 summary

Migrated all memory files to have L0 comment as first line,
consistent with upstream PAI convention.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

memory/cog-meta/scenario-calibration.md

@@ -1,5 +1,5 @@
-# Scenario Calibration
 <!-- L0: Prediction accuracy tracker for decision scenarios -->
+# Scenario Calibration
 
 <!-- Updated by /reflect when scenarios resolve. -->