feat(backend): GET /api/reconciliation/unmatched

backend/src/cyclone/api.py

@@ -499,6 +499,18 @@ def list_claims(
     }
 
 
+@app.get("/api/reconciliation/unmatched")
+def get_reconciliation_unmatched() -> dict:
+    """Return unmatched Claims (left) and unmatched Remittances (right).
+
+    Powers the reconciliation review surface: every Claim with no
+    paired Remittance appears on the left, every Remittance with no
+    paired Claim appears on the right. The two lists are always present
+    (empty list, never absent) so the UI can index unconditionally.
+    """
+    return store.list_unmatched(kind="both")
+
+
 @app.get("/api/remittances")
 def list_remittances(
     request: Request,