feat: add decision.point event type, decision logger, and run replay script

- archeflow-decision.sh: convenience wrapper for logging PDCA decision points
- archeflow-replay.sh: timeline view and weighted what-if replay for recorded runs
- archeflow-event.sh: add decision.point usage example
- archeflow-dag.sh: render decision.point events in DAG output

lib/archeflow-event.sh

@@ -8,6 +8,9 @@
 #   ./lib/archeflow-event.sh 2026-04-03-der-huster agent.complete plan creator '{"duration_ms":167522}' 2
 #   ./lib/archeflow-event.sh 2026-04-03-der-huster phase.transition do "" '{"from":"plan","to":"do"}' 3,4
 #   ./lib/archeflow-event.sh 2026-04-03-der-huster fix.applied act "" '{"source":"guardian"}' 8
+#   ./lib/archeflow-event.sh 2026-04-03-der-huster decision.point check guardian \
+#     '{"archetype":"guardian","input":"diff","decision":"needs_changes","confidence":0.85}' 7
+#   # Or use: ./lib/archeflow-decision.sh <run_id> <phase> <arch> '<input>' '<decision>' <confidence> [parent]
 #
 # Parent seqs: comma-separated seq numbers of causal parent events (DAG).
 #   "2"   → single parent [2]