[Org Overview] Omit internal account transfer transactions from Expense & Revenue stats

## Problem

Right now, the Expense & Revenue stats are very simple. If a transaction is positive, then it's included as revenue. If it's negative, then it's an expense. Because of this, the Expense & Revenue stats on the organization home page are not helpful for HQ organizations because they are artificially inflated.

## Desired UX

Disbursements for the purpose of internal account transfer should be omitted from the Expense & Revenue stats.

## Solution

1. We need to categorize Disbursements by their intended purpose. For example:
- Repayment of an expense (e.g. Claude paid by HQ; and HCB disburses)
- Funding of an event/project
- Returning extra funds from an event/project
- NOTE: categories _**should**_ be more generic than the reason I mentioned above, but they still need to capture the intention behind the money movement from an accounting perspective; and granular enough for us to help organizations understand their finances.
2. We need to understand which categorizes needs to be omitted from the Expense & Revenue stats
3. Then, actually omit them from the Expense & Revenue stats

Start by locating the organization home page's Expense & Revenue stats and the code that represents Disbursements. Review how transaction direction currently determines revenue or expense, then define generic accounting-purpose categories and identify which category represents internal account transfers. Done means those transfers are omitted without excluding legitimate expenses or revenue.

Written by the indexing model from the issue text.