fix(workspace): nest Bank Statements under Accounting

User feedback: a standalone top-level workspace doesn't surface inside
the existing ERPNext module tiles. Putting it under Accounting (next to
Financial Reports) matches user mental model — bank statement work is
already a financial activity.

After migrate, Bank Statements shows up as a sub-page in the Accounting
sidebar group, alongside Financial Reports.

jey_erp/jey_erp/workspace/bank_statements/bank_statements.json

@@ -132,12 +132,12 @@
  "name": "Bank Statements",
  "number_cards": [],
  "owner": "Administrator",
- "parent_page": "",
+ "parent_page": "Accounting",
  "public": 1,
  "quick_lists": [],
  "restrict_to_domain": "",
  "roles": [],
- "sequence_id": 30.0,
+ "sequence_id": 6.0,
  "shortcuts": [
   {
    "color": "Blue",