fix: use shared scratch helpers in dev-agent and action-agent to eliminate duplicates (#262)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

predictor/predictor-run.sh

@@ -65,12 +65,11 @@ about CI health, issue staleness, agent status, and system conditions.
 ## Project context
 ${CONTEXT_BLOCK}
 ${SCRATCH_CONTEXT:+${SCRATCH_CONTEXT}
-}
+}${SCRATCH_INSTRUCTION}
+
 ## Formula
 ${FORMULA_CONTENT}
 
-${SCRATCH_INSTRUCTION}
-
 ${PROMPT_FOOTER}"
 
 # ── Run session ──────────────────────────────────────────────────────────