Improved navigation in the giving section

We've added a new "My contributions" tab to the "Giving" section navigation (visible only to treasurers). This makes it clearer when you're viewing your own contributions — a page that's accessible to all members — before navigating to other treasurer-only sections like Deposits, Statements, and Receipts. A small divider also helps visually separate this page from the rest of the treasurer-only tools.

We also moved the "Settings" link out of the navigation and onto the "Receipts" page, since that's what those settings pertain to, and they don't need to be accessed frequently.