docs: codify merge proof standard (#32)

OPERATIONS.md

@@ -41,3 +41,9 @@ ps aux | grep -E "claude-loop|gemini-loop|timmy-orchestrator" | grep -v grep
 - Health Monitor: every 5m, haiku (not opus!)
 - DPO export / training support jobs: explicit model, explicit task, no hidden defaults
 - All crons MUST specify model explicitly. Never inherit default.
+
+## Proof Standard
+- visual changes require screenshot proof
+- keep screenshots and binary media out of Gitea backup unless explicitly required
+- CLI/verifiable changes must reference the exact command output, log path, or observable state proving the claim
+- see `CONTRIBUTING.md` for the merge gate