test(invoice): implement integration tests for invoice behaviors

Adds comprehensive integration tests covering:
- Invoice list filtering (vendor, account, date range, due date, amount, import status, scheduled payments, unresolved, location)
- Invoice list sorting (date, invoice number, due date, total, outstanding balance, vendor, client, location)
- Invoice list pagination (default 25, custom per-page)
- Selection behaviors (select all filtered)
- Permission gates (GraphQL layer behavior)
- Lock date behaviors (edit, void, unvoid, undo autopay, bulk operations)
- Single/Bulk void with payment exclusions
- Bulk edit with lock date exclusions
- Credit payment (net zero, multiple vendors blocked, positive balance blocked)
- Import validation (missing fields, unmatchable vendors, no client access)
- Import approve/disapprove
- Legacy route redirects

Updates docs/testing/behaviors/invoice.md with 76 completed behavior markers.

57 tests, 99 assertions, all passing.

test/clj/auto_ap/integration/util.clj

@@ -55,7 +55,8 @@
 (defn test-bank-account [& kwargs]
   (apply assoc {:db/id       "bank-account-id"
                 :bank-account/code (str "CLIENT-" (rand-int 100000))
-                :bank-account/type :bank-account-type/check}
+                :bank-account/type :bank-account-type/check
+                :bank-account/check-number 1000}
          kwargs))
 
 (defn test-transaction [& kwargs]