Save to Are.na per Vlad

This extension adds a small save icon ("**") when you hover over images on most websites. Clicking the icon initiates a process to save that image to one of your Are.na boards.

## Features

* **Hover-to-Save:** An overlay appears on image hover, providing a quick save button.
* **Are.na Authentication:** Securely connects to your Are.na account using OAuth 2.0 (Authorization Code flow). You only need to log in once.
* **Board Selection UI:** After clicking the save button, a UI appears within the overlay allowing you to:
* View your 3 most recently updated Are.na boards (fetched initially when the list is empty).
* See the list update dynamically as you save items using the extension.
* Search for any of your boards by name.
* **Visual Feedback:** The save button provides visual cues for loading, success (✅), failure (❌), and authentication required (🔑).