Enhancement: Additional External URI Protocol Recognition

[xrxca]

Currently only http:// https:// and mailto: links are recognized as external links.
It would be nice if other external URIs where recognized specifically:

• ssh: Secure Shell
• tel: Telephone

I've been trying NoteDiscovery for my technical notes and so far I quite like it, however for console access to virtual machines and servers, I use ssh: URI's extensively in proxmox descriptions and would like to be able to use them in my notes. Also my desktop is setup to pass tel: links to my phone system, and my mobile handles tel: links as well.

I'll admit that the ssh: scheme is not commonly used, and there are probably other protocols that someone else would use, so maybe a config setting with a list of prefix's that are considered external besides http://, https://, //, mailto:, and /api/

I tested this and it seems adding tel: to the list works, but adding ssh: doesn't (no longer thinks it a note, but doesn't handle the link at all, maybe it's an upstream issue),
frontent/app.js would need to be modified (~2499)
from:

// Check if it's an external link or API path (media files, etc.)
if (href.startsWith('http://') || href.startsWith('https://') || href.startsWith('//') || href.startsWith('mailto:') || href.startsWith('/api/')) {
    return; // Let external links and API paths work normally
}

to:

// Check if it's an external link or API path (media files, etc.)
if (href.startsWith('http://') || href.startsWith('https://') || href.startsWith('//') || href.startsWith('mailto:') || href.startsWith('tel:') || href.startsWith('ssh:') || href.startsWith('/api/')) {
    return; // Let external links and API paths work normally
}

[xrxca]

It seems the ssh: issue is with the rendering, whereas tel: renders correctly, but tries to open as a note when clicked unless the above change is made, any colon in a link that isn't recognized gets the href dropped..

[Tel Link](tel:+15555551212)
[File Link](file://server/file)
[SSH Link](ssh://user@host:22) 
<a href="ssh://user@host:22">HTML SSH Link</a>
[Junk 1](junk:1)
[Junk 2](junk2)

Renders as:

<a href="tel:+15555551212">Tel Link</a><br>
<a>File Link</a><br>
<a>SSH Link</a><br>
<a>HTML SSH Link</a><br>
<a>Junk 1</a><br>
<a href="junk2">Junk 2</a>

[xrxca]

So the main culprit is DOMPurify, it strips any unknown protocols (which ssh: is considered one of)
I've now patched my version to allow unknown protocols, and added ssh: and tel: into the External link check as above, and it seems to work.

html = DOMPurify.sanitize(html);

becomes

html = DOMPurify.sanitize(html, {ALLOW_UNKNOWN_PROTOCOLS: true});