Updates the image building workflow to improve reliability and readability.
Changes:
- Replaced the complex `moby/buildkit` container-in-container execution with standard Docker build and push steps.
- Added explicit checkout, login, and build steps to the job matrix.
- Improved the change detection logic:
- Added input sanitization (whitespace trimming) for manually triggered builds.
- Added comments explaining the directory diff logic.
- Updated job titles and comments to English for consistency (e.g., "Detect modified images" instead of "Détection des images modifiées").
- Added `fail-fast: false` to the matrix strategy so one failed build doesn't stop others.
