`icon.svg` is not included in `*.charm` file

[Abuelodelanada]

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• I've verified that this bug isn't described by any existing issues.

Bug description

charmcraft pack does not include icon.svg in the final *.charm files.

According to this post the file icon.svg should be included in *.charm file.

Besides that, according to this doc the icon should be 100x100px.

Because of this, charms end up without a logo in charmhub.io

Steps to reproduce

1. Clone this repo: https://github.com/canonical/opentelemetry-collector-operator/
2. run charmcraft pack
3. Verify that icon.svg is not in the *.charm files

Environment

charmcraft 4.0.1

[dimaqq]

I think this got broken earlier.
For example, this older published version contains the icon:

Archive:  vault-k8s_r248.charm
  Length      Date    Time    Name
---------  ---------- -----   ----
    11594  2024-07-10 07:58   icon.svg
...

And this one doesn't:

Archive:  vault-k8s_r502.charm
  Length      Date    Time    Name
---------  ---------- -----   ----
      659  2026-02-19 09:39   config.yaml
...

And this one doesn't:

Archive:  vault-k8s_r446.charm
  Length      Date    Time    Name
---------  ---------- -----   ----
     2140  2025-09-26 00:13   actions.yaml
      738  2025-09-26 00:13   dispatch
...

I think that the icon is sticky on charmhub.io, if a charm ever pushed a version (or a latest version) with an icon, it doesn't matter that newest artefacts are missing an icon. Either that, or the icon used to be passed out of band.