[FIN-02] Implement Transaction Category Management

[kilip]

Description

Implement CRUD for transaction categories (income and expense types).

Subtasks

• FIN-02-ST-01 Implement TransactionCategoryService CRUD with role check
• FIN-02-ST-02 Build category management UI at /setting/categories
• FIN-02-ST-03 Display categories as dropdown in transaction form

Acceptance Criteria

• FIN-02-AC-01 Only super-admin and treasurer can manage categories
• FIN-02-AC-02 Categories have a type: income or expense
• FIN-02-AC-03 Soft delete applied

Technical Notes

• Docs: PRD#63-parish-financial-recording · ERD#24-finance
• Screen spec: docs/screen.md → Transaction Category Management