## Summary
This PR refactors the `Buffer.concat` implementation to use modern C++
spans for safer memory operations and adds proper error handling for
oversized buffers.
## Changes
- **Use spans instead of raw pointers**: Replaced pointer arithmetic
with `typedSpan()` and `span()` methods for safer memory access
- **Add MAX_ARRAY_BUFFER_SIZE check**: Added explicit check with a
descriptive error message when attempting to create buffers larger than
JavaScriptCore's limit (4GB)
- **Improve loop logic**: Changed loop counter from `int` to `size_t`
and simplified the iteration using span sizes
- **Enhanced test coverage**: Updated tests to verify the new error
message and added comprehensive test cases for various Buffer.concat
scenarios
## Test Plan
All existing tests pass, plus added new tests:
- ✅ Error handling for oversized buffers
- ✅ Normal buffer concatenation
- ✅ totalLength parameter handling (exact, larger, smaller)
- ✅ Empty array handling
- ✅ Single buffer handling
```bash
./build/debug/bun-debug test test/js/node/buffer-concat.test.ts
# Result: 6 pass, 0 fail
```
🤖 Generated with [Claude Code](https://claude.ai/code)
---------
Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
