feat: improve markdown link handling

[eclecticpassions]

Hi,

I wanted these two features for a long time as I'm very used to pasting links directly into selected text in VS Codium and Obsidian.

With some help from qwen2.5-coder, I figured how to add the two features into the textarea/index.js file. I tested it locally and it seems to be working! But I'd appreciate your feedback to see if it's worth adding to Indiekit main or if there's any errors/improvements.

My two additions:

• Improve how Markdown links are handled when the "link" button is pressed by removing the placeholder https:// inside the (). Because, then I have to select the https:// and then paste the link from my clipboard. The extra step is a bit cumbersome (to me). Now, when the button is pressed, the cursor jumps to an empty () after the [link text] and ctrl+v will paste the link in, making it quicker and less fiddly.

• Added new feature of generating Markdown links automatically a link is pasted into highlighted text. This means it doesn't require using the mouse to press the link button in the editor toolbar (like in GitHub).

Thanks @paulrobertlloyd!

Edit: correct wrong link to GitHub example

[eclecticpassions]

Hi @paulrobertlloyd, is there anything I can do to help get this reviewed or merged if deemed suitable, as it's been a while? If it's not suitable, I will go learn how to maintain my own separate version so I can use the Markdown editing features. Thanks!

[paulrobertlloyd]

Am slowly getting back to being able to work on this project; will take a look at this PR soon.

[eclecticpassions]

Thanks @paulrobertlloyd for checking it! Very happy to see you. Appreciate it. ;)

[paulrobertlloyd]

Thanks so much for this @eclecticpassions, these are great quality of life improvements!

I spotted (and fixed) one issue: if you click the link icon with no text selected, you wouldn’t get any output. I have updated the behaviour so that clicking the link button with no text selected returns []() (with the cursor placed within the brackets). If you have text selected, then the selected text gets updated ([selected text]()).

I have also updated the code to follow linting rules, and call the already provided editor.codemirror reference instead of querying .CodeMirror.