Add answer key for Debugging workshop

[beagandica]

Summary

Complete answer key for the C Debugging workshop covering all tutorial bugs and three algorithm exercises.

Changes

New file: \content/english/debugging/answer-key.md\

Tutorial section (bugs already shown in expand blocks, now consolidated):

• Binary Search - Recursive call searched upper half instead of lower half
• Quicksort - Missing \p1++\ after swap in partition loop
• Vector memory - Forgot to update \list->__arr\ after realloc

Exercise solutions (correct implementations):

1. Binary Tree - treeAdd, treeRemove (3 cases: 0/1/2 children), findMin with sentinel node
2. Binary Heap - heapAdd (sift up) and heapRemoveMax (sift down) for 1-indexed max heap
3. Burrows-Wheeler Transform - Suffix array construction + safe modulo pattern

Teacher resources:

• Common bugs to watch for per exercise
• GDB and Valgrind quick reference table
• C remainder vs modulo operator warning

Languages affected

• English (primary)
• Brazilian Portuguese translation exists (C code is language-agnostic)

Testing

• Hugo build passes
• All language versions checked
• 10-model QA passed (3 clean passes)
• Follows answer key format (hidden: true, weight: 15)

Note

Exercise implementations are based on the algorithm descriptions in the workshop. The Replit links (Exercise 1-3) returned 404 during development — the exercise environments may need to be verified separately.