Add the {size} template variable to the network-icon spec.

[sadiepowell]

As discussed on IRC.

[jwheare]

Might be worth adding something like

Servers advertising a URL with the {size} variable SHOULD serve a default size when the literal string {size} is requested, in order to support clients that do not perform URL template interpolation.

And change the client "MUST replace" to a MAY.

[jwheare]

Will aim to merge this next week.

[emersion]

Are there implementations of this?

[emersion]

It doesn't seem like it uses the {size} parameter added in this PR?

https://github.com/squidowl/halloy/pull/1781/changes#diff-efaa5e2d4f638382602a1303ccf0f80bc2cd54cd68d4c77f8381b2d3d5a2beeeR1352

[jwheare]

IRCCloud implements it.

Note in this example, the value is ignored and a different fixed size image is being returned, which is perfectly valid.