Release v0.4.1: TypeScript Compilation Fixes

This patch release fixes TypeScript compilation errors in the VS Code extension
to ensure clean builds.

Changes:
- Fixed instruction.behavior possibly undefined error in isa-validator.ts
- Removed unused variables from test files to eliminate TypeScript warnings

1. TypeScript Compilation Fixes

Fixed TypeScript compilation errors:
- Fixed TS18048: Added null check for instruction.behavior before accessing
  instruction.behavior.statements in isa-validator.ts line 288
- Fixed TS6133: Removed 7 unused variable declarations (errors, functionErrors)
  from builtin-functions.test.ts

Technical Details:
- Updated isa-validator.ts: Added instruction.behavior && check before
  accessing instruction.behavior.statements
- Cleaned up builtin-functions.test.ts: Removed unused variables that were
  causing compilation warnings

Benefits:
- Clean TypeScript compilation with no errors or warnings
- Improved code quality and maintainability
- Ensures VS Code extension builds successfully

Files Changed:
- Modified: vscode_extension/isa/packages/language/src/isa-validator.ts
  (added null check for instruction.behavior)
- Modified: vscode_extension/isa/packages/language/test/builtin-functions.test.ts
  (removed unused variables)

Test Results:
- Python: 216 tests passing
- VS Code Extension: All tests passing
- TypeScript compilation: Clean build with no errors or warnings

Version Updates:
- pyproject.toml: 0.4.0 → 0.4.1
- vscode_extension/isa/package.json: 0.4.0 → 0.4.1
- vscode_extension/isa/packages/extension/package.json: 0.4.0 → 0.4.1
- vscode_extension/isa/packages/language/package.json: 0.4.0 → 0.4.1
- README.md: Version badge updated to 0.4.1
- vscode_extension/isa/packages/extension/README.md: Version badge updated to 0.4.1

Breaking Changes: None
Migration: No changes required, this is a bug fix release
