refactor: add complete type annotations to build.py (Closes #7)

[18680368135]

Summary

Add complete Python type annotations to all 22 functions in build.py for improved static analysis.

Changes

• Added type annotations to all 22 functions
• Used from future import annotations for forward refs
• Used specific types (str, int, bool, Path, dict, list, tuple)
• No Any type usage
• All parameters and return types annotated

Testing

• Verified valid Python syntax (ast.parse)
• Verified 22 typed functions (>= 10 required)
• Verified no Any usage
• Verified typing imports present
• Verified all params annotated (except self)
• Verified all functions have return annotations

Checklist

• Relevant modules affected by these changes build locally
• Tests pass locally
• Diagnostic build log is committed in this PR
• Documentation has been updated, if applicable
• Configuration or schema changes are documented, if applicable
• No generated build artifacts are committed, except the required diagnostic build log
• Changes are scoped to the PR purpose and avoid unrelated cleanup
• Security, privacy, and error-handling implications have been considered

---

• I would like to request that my diagnostic build log is removed before merging