Translation make targets point at a directory that does not exist

Problem

Every localization target in backend-plugin-sample/Makefile does cd sample_plugin, but there is no sample_plugin/ directory. The package lives at backend-plugin-sample/src/openedx_plugin_sample/. The path predates the renames in a9f4b8d (platform-plugin-sample -> backend-plugin-sample / openedx_plugin_sample).

So all of these fail immediately with cd: no such file or directory:

• extract_translations
• compile_translations
• detect_changed_source_translations
• dummy_translations
• pull_translations (the atlas branch, which also references sample_plugin/conf/locale)
• and therefore build_dummy_translations and validate_translations

Nothing in CI runs these targets, which is why the breakage has gone unnoticed.

Also in scope

install_transifex_client ends with:

git checkout -- LICENSE README.md ## overwritten by Transifex installer

There is no LICENSE in that directory either -- the file is LICENSE.txt.

Suggested fix

Point the targets at src/openedx_plugin_sample, fix the atlas locale paths to match, and correct the LICENSE.txt filename. Worth considering whether validate_translations should run in CI so this cannot silently rot again.

Note that the plugin does not currently mark any strings for translation, so part of this work is deciding whether the i18n scaffolding should be exercised as a demonstration (this repo is meant to be an example of the plugin interfaces) or removed until there is something to translate.

Start in backend-plugin-sample/Makefile and inspect the listed localization targets, including the atlas branch of pull_translations and install_transifex_client. Verify the package and locale paths under src/openedx_plugin_sample, then run the affected targets. Done means the targets no longer fail on missing directories or LICENSE.txt, with the issue's decision on exercising or removing the translation scaffolding addressed.