feat: add us-cpa review workflow

docs/us-cpa.md

@@ -109,7 +109,7 @@ Behavior:
 - `question` emits answered analysis output
 - `prepare` emits a prepared return package summary
 - `export-efile-ready` emits a draft e-file-ready payload
-- `review` is still scaffolded
+- `review` emits a findings-first review result
 - `fetch-year` emits a downloaded manifest location and source count
 
 ## Question Engine
@@ -180,6 +180,21 @@ Current export behavior:
 - includes attachment manifest
 - includes unresolved issues
 
+## Review Workflow
+
+Current `review` implementation:
+
+- recomputes the return from current case facts
+- compares stored normalized return values to recomputed values
+- checks whether required rendered artifacts are present
+- flags overlay-rendered artifacts as requiring human review
+- sorts findings by severity
+
+Current render modes:
+
+- `--style conversation`
+- `--style memo`
+
 ## Scope Rules
 
 - U.S. federal individual returns only in v1