Tox popup aligment

When a user selects text inside the editor, the AI plugin's selection toolbar (opened via the aishortcuts button/menu — the floating popup offering "Summarize", "Proofread", "Change tone", "Translate", etc.) is normally anchored in the middle of the selected text, which works correctly for longer, single-line selections. However, when the selected text is short and wraps across multiple lines (e.g. a couple of words that break into 2 lines due to column width), the popup instead it renders centered in the middle of the editor/browser window, which looks disconnected from the actual selection and is visually confusing for the user.

Suggestion: the popup should be aligned in the middle, based on widest selected line.