Move "Add Cur. Page" Button to Top of Playlist View

Request

in the individual playlist view of the popup window, move the "add current page to playlist" button from the bottom to the top. shrink it so that it's the same size and shape as the "export playlists" buttons on the main view - shorten the wording of the button if necessary (like "add cur. page" or something similar).

Changes

popup/popup.html

Moved the add-current-page-container div fully outside of .playlist-view-container, placing it above the card (mirroring how .export-container sits above .playlists-container).
Added x-bind="addCurrentPageContainer" to the container for visibility control.

popup/popup.css

Restyled .add-current-page-container as a flex row (matching .export-container) so the button is auto-sized rather than block-stretched.
Restyled .add-current-page-btn to match the export buttons: padding: 8px 12px, border-radius: 4px (was 6px), removed width: 100%, removed hover animation.

popup/popup.js

Added addCurrentPageContainer binding with x-show tied to currentView === "playlist".
Shortened all button text strings:
- Default: "Add Current Page" → "Add Cur. Page"
- YouTube only: "Add Current Page (YouTube only)" → "Add Cur. Page (YT only)"
- Normal state: "Add Current Page to Playlist" → "Add Cur. Page"
- Error state: "Unable to get current page" → "Unable to get page"