fix(gnoweb): transform relative args links

[alexiscolin]

Description

This PR fixes issue #3865 by implementing proper transformation of relative links that start with ":" into full gnoweb URLs. This ensures proper URL resolution and maintains the gno.land URL structure.

Changes

• Added TransformRelArgsURL function to handle relative links starting with ":"
• Added comprehensive test cases covering various URL scenarios
• Updated documentation with clear examples

Example

from https://gno.land/r/demo/polls URL:

Input:  [link text](:2/votes)
Output: [link text](/r/demo/polls:2/votes)

---

Fixes: #3865

[Gno2D2]

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Codecov Report

Attention: Patch coverage is 86.36364% with 3 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
gno.land/pkg/gnoweb/webclient_html.go	86.36%	2 Missing and 1 partial ⚠️

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[alexiscolin]

Even simpler 👍 Thank you @gfanton

[gfanton]

Should we document this somewhere? Otherwise, it looks good! Thanks!

[leohhhn]

In r/docs/markdown we can have a section for links, ie abs vs relative vs special chars :

[moul]

I had a similar idea at one point but then decided to focus on creating good p/ libraries to manage this for us. I still believe this idea could be very beneficial, but I prefer blocking so we can discuss it with more people during a review meeting.

[ajnavarro]

@moul I don't know if you are referring to these two gno packages or other things:

• https://gno.land/p/demo/fqname$source&file=fqname.gno
• https://gno.land/p/moul/realmpath$source&file=realmpath.gno

But none of them fixes the problem we are having with relative paths not working. It is impossible to fix at gno code level because for that you must know from where your code is called.

Implementing the proxy pattern, I needed to delegate the Render call to a struct. That Render method can be called from gno.land/r/gov/dao or gno.land/r/gov/dao/v3/impl. Not having relative paths working makes it impossible to properly write the markdown code for that case.

In any case, I think we need relative paths, and we don't have them. What I saw was people having to hardcode the name of the package realm on their code to have it working properly.

Examples:

• https://github.com/gnolang/gno/blob/master/examples/gno.land/p/demo/microblog/microblog.gno#L21
• https://github.com/gnolang/gno/blob/master/examples/gno.land/p/demo/blog/blog.gno#L16
• https://github.com/gnolang/gno/blob/master/examples/gno.land/r/demo/art/millipede/millipede.gno#L43

[moul]

I was referring to this one: https://github.com/gnolang/gno/blob/master/examples/gno.land/p/moul/realmpath/realmpath.gno

I don't understand how we can say, "you must know where your code is called," while also mentioning "relative links." If something is relative, it pertains to the current rendering realm, which is the one from which you are executing Render(). Is that correct?

Perhaps realmpath should, like the txlink package, allow specifying an arbitrary realm as the caller. Alternatively, it could have another constructor that accepts previousrealm. I agree that this approach seems more complex than necessary. However, using relative links in a context where we can create rendering helpers appears more dangerous than explicitly creating full paths.

That said, I think it's reasonable to view a realm as akin to a domain name. In this context, the notion of a relative link makes sense if we consider each realm to be a unique domain.

Can we explore how using realmpath (or another solution) could address your case before considering this PR?