Persistent directories mechanism is broken

[tosfos]

Describe the bug

Summary: The persistent directories mechanism doesn't work. That's because in CanastaBase's extensions-skins.php runs before extensions are installed and targets a non-mounted volume location.

Description: During Docker image build, the extensions-skins.php script attempts to handle "persistent directories" defined in extension YAML configurations. However, this logic has two critical flaws:

1. Wrong timing: The persistent directories code executes before extensions are cloned, so the directories don't exist yet when the script tries to move them.

2. Wrong location: The symlinks point to $MW_VOLUME/canasta-$type/... which resolves to /mediawiki/canasta-extensions/... - a location that is not mounted.

This breaks the entire persistent directories feature, affecting any extension that declares persistent directories (currently SMW with the config/ directory and Widgets with compiled_templates/).

Steps to reproduce the behavior:

Look at lines 53-59

Expected behavior

The persistent directories mechanism should work.

System info

All (infrastructure issue)

[yaronkoren]

@tosfos - the first issue was (I think) fixed in #44, and the PR at CanastaWiki/Canasta-DockerCompose#71 attempts to fix the second issue. Could you please review that one?

[tosfos]

Likely fully fixed in #44