[Sub-Issue #549.5] Move M12 (Debugging) to S10 Extra as optional module

[SkafteNicki]

Parent Issue

Part of #549 - New learning session on data engineering

Phase

Phase 2 - Restructure Existing Sessions

Description

Move the Debugging module (M12) from S4 to S10 Extra and mark it as optional. The rationale is that debugging will be taught in real-life during lectures rather than as a standalone module.

Tasks

• Move s4_debugging_and_logging/debugging.md → s10_extra/debugging.md
• Mark the module as optional in the content/frontmatter
• Move any associated exercise_files/ directory
• Update S10 README.md to include the debugging module
• Update all internal cross-references to the debugging module
• Search for references in other modules that link to debugging
• Update any relative paths in the moved module
• Verify all links and references still work

Files to Update

• s4_debugging_and_logging/debugging.md (move to s10_extra/)
• s10_extra/README.md
• Any modules that reference the debugging module
• Any exercise files

Dependencies

• Should be done after Phase 1 is complete (S11 modules created)

Acceptance Criteria

• Debugging module successfully moved to S10
• Module is clearly marked as optional
• All links and references updated and working
• S10 README properly lists the new module
• No broken links remain in the codebase