Mobile push notifications

I've been speaking to @thedev132 today about HCB Mobile notifications and to get this done we need to properly revamp HCB's end of notifications which has been discussed before but never happened. This issue will be sub-divided into 2 main sections _for now_:

1. HCB's notification panel. Right now, this panel is quite bland and doesn't allow the user to properly customize a varerity of options which are quite basic. As discussed in this old issue https://github.com/hackclub/hcb/issues/5367#issuecomment-2019199118, we would need to develop a proper UI that allows users to customize as much as possible without over-cluttering the screen with 2 million options. Ideally, we want the user to be able to customize getting SMS, Email, HCB Mobile notif's for major categories such as:

- Transfers, Checks, Disbursements, Reimbursements, Team updates etc
- Comments
- Only your transaction or all transactions under your orgs.

Figuring out how this can be developed can be discussed further later though figuring out how the MVP for delivery frequencies along with how we will handle all of this cleanly could be handled first.

2. HCB Mobile Integration. To be able to handle notifications via HCB Mobile, we will need to use HCB as a server being able to use the current notification settings set by the user, and relay it down to the HCB Mobile app along with handling the click within the app. For this to happen, we can use a library like https://github.com/expo-community/expo-server-sdk-ruby which will be able to interface with HCB Mobile's end (https://docs.expo.dev/versions/latest/sdk/notifications/). Though this is still a far away ahead until the main HCB's notification's section gets revamped.

No files, tests, or entry points are identified. Start by mapping the existing notification panel and user settings, then review the proposed HCB Mobile integration and Expo server SDK; the issue is done only when a defined MVP covers notification preferences, delivery frequencies, and mobile delivery.

Written by the indexing model from the issue text.