[Feature]: Add an item to share with the community to identify that it is available to borrow

### Problem to solve

When creating a new item to share, we want to include:

* Item name
* More detailed description with model number or other pertinent information
* The location of where it is currently stored
* optionally: a picture to upload of the item

### Desired outcome

A feature on the website to create a listing for a new item that can be shared with the required information (and potentially additional optional info) that will then be listed as an available item

### Proposed solution

_No response_

### Alternatives considered

_No response_

### Additional context

_No response_

### Before submitting

- [x] I searched existing issues and did not find an equivalent request.

Start by mapping the existing website's item and listing creation entry points, including how item data is stored and displayed. Define the listing fields for name, detailed description, storage location, and optional picture, then verify that a created listing appears as an available item with the required information.

索引モデルが issue の本文から書いたものです。