ci: update runner-image + repo path to public/ namespace

Repos moved to public/ on Gitea: public/runner-image (CI image)
and public/code-crispies (this repo). Updates workflow image refs,
spec hyperlinks, README, and compose tags.

specs/003-flexbox-task-wording/spec.md

@@ -1,6 +1,6 @@
 # fix: remove answers from flexbox task descriptions (copy-paste score 95%)
 
-**Issue**: [libretech/code-crispies#3](https://git.librete.ch/libretech/code-crispies/issues/3)
+**Issue**: [public/code-crispies#3](https://git.librete.ch/public/code-crispies/issues/3)
 **State**: open
 **Author**: libretech
 **Labels**: none

specs/004-validation-messages/spec.md

@@ -1,7 +1,7 @@
 # fix: validation error messages reveal the solution instead of guiding learning
 
-**Issue:** [#4](https://git.librete.ch/libretech/code-crispies/issues/4)
-**Repository:** libretech/code-crispies
+**Issue:** [#4](https://git.librete.ch/public/code-crispies/issues/4)
+**Repository:** public/code-crispies
 **Author:** libretech
 **State:** open
 **Labels:** none

specs/009-colors-boxmodel-tasks/spec.md

@@ -1,6 +1,6 @@
 # fix: rewrite colors and box-model task descriptions to remove copy-paste answers
 
-**Issue**: [libretech/code-crispies#9](https://git.librete.ch/libretech/code-crispies/issues/9)
+**Issue**: [public/code-crispies#9](https://git.librete.ch/public/code-crispies/issues/9)
 **State**: open
 **Author**: libretech
 **Labels**: none

specs/012-filters-tasks/spec.md

@@ -1,7 +1,7 @@
 # fix: rewrite CSS Filters tasks to describe visual outcomes instead of exact code
 
-**Issue:** [#12](https://git.librete.ch/libretech/code-crispies/issues/12)
-**Repository:** libretech/code-crispies
+**Issue:** [#12](https://git.librete.ch/public/code-crispies/issues/12)
+**Repository:** public/code-crispies
 **Author:** libretech
 **State:** open
 **Labels:** none