feat(ECR-007): Wyckoff Live Structure with Confirmed/Live isolation

Add live.py lifecycle and event candidates; assemble confirmed vs live
in engine; Summary partition; execution_signal source=confirmed only.
Keep strategies untouched; do not lower Confirmed thresholds for Live.

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/HANDOFF/ECR-007-engineer-to-reviewer.md

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+# Handoff — Engineer → Reviewer
+
+**ECR:** ECR-007  
+**Date:** 2026-08-07  
+
+## Delivered
+
+- `chanlun/analysis/wyckoff/live.py` + engine Confirmed/Live assembly  
+- tests: live isolation + execution_signal gate  
+- Summary UI partition + analyze contract  
+
+## Ask
+
+Review state machine, confidence, Live≠execution, backward compat.