feat: add assessment workbench and September reconciliation

Preserve August hydrogen revision and September audit evidence; calculate interrupted vehicle history across all prior months. Record remaining carry-policy and layout-baseline discrepancies.

calc_engine.py

@@ -87,7 +87,7 @@ def calc_jan_carryover(G1):
         g['cum_a'] = g['实际']
         g['cum_q'] = g['实际'] >= g['应考核'] and g['应考核'] > 0
 
-def calc_month(month, G_all, all_data, G_prev, G_cur):
+def calc_month(month, G_all, all_data, G_prev, G_cur, *, cumulative_history=False):
     """通用月计算: 结转/补发/累计补发/当月"""
     prev_m = month - 1
     days_m = DAYS[month]
@@ -100,8 +100,17 @@ def calc_month(month, G_all, all_data, G_prev, G_cur):
         gp = G_prev.get(k)
 
         # 累计
-        cum_t = (gp['cum_t'] if gp else 0) + gm['应考核']
-        cum_a = (gp['cum_a'] if gp else 0) + gm['实际']
+        if cumulative_history:
+            # Historical backpay scans all prior months, so its qualifying
+            # mileage must cover that same vehicle/owner history, including
+            # periods before an interruption. Do not reset at a missing month.
+            history = [G_all[m][k] for m in range(1, month) if k in G_all.get(m, {})]
+            cum_t = sum(g['应考核'] for g in history) + gm['应考核']
+            cum_a = sum(g['实际'] for g in history) + gm['实际']
+        else:
+            # Retained for reproducing already-settled legacy workbooks.
+            cum_t = (gp['cum_t'] if gp else 0) + gm['应考核']
+            cum_a = (gp['cum_a'] if gp else 0) + gm['实际']
         cum_q = cum_a >= cum_t and cum_t > 0
 
         # 结转: carry × 1 (整月, 不折算)