Add cppcheck static analysis to CI workflow

[angeloINTJ]

What

Add a cppcheck step to .github/workflows/build.yml to catch bugs at CI time.

Why

cppcheck is a lightweight, zero-config static analyzer for C/C++. It catches:

• Buffer overflows
• Memory leaks
• Null pointer dereferences
• Uninitialized variables
• Suspicious expressions

For a firmware project handling network input, this is a critical safety net.

How

1. Add new steps after "Set up Python" in .github/workflows/build.yml:

   - name: Install cppcheck
     run: sudo apt-get update && sudo apt-get install -y cppcheck
   
   - name: Static Analysis
     run: |
       cppcheck --enable=all --inconclusive --error-exitcode=1 \
         -I src/ --suppress=missingIncludeSystem \
         --suppress=unusedFunction \
         src/ 2>&1 | tee cppcheck.log

2. Fix any existing warnings (or add suppressions with comments explaining why)
3. Verify the CI passes: check GitHub Actions on your fork

Acceptance

• cppcheck step added to build.yml
• CI passes green with zero cppcheck errors
• Any necessary suppressions have explanatory comments
• Build time impact is under 30 seconds

References

• .github/workflows/build.yml — existing CI workflow
• cppcheck manual