fix: StreamedBinaryFileResponse — Incorrect Chunking Logic

[s2x]

Summary

Fixes incorrect chunking logic in StreamedBinaryFileResponse by simplifying the inner while loop that was unnecessarily complex and had a bug where $length was decremented by $read instead of actual data length.

Changes

• Simplified the chunking logic in src/Protocol/Http/Response/StreamedBinaryFileResponse.php:36-52
• Removed redundant inner while ('' !== $data) loop that only executed once in most cases
• Fixed length calculation: uses strlen($data) instead of $read because fread() may return fewer bytes than requested
• Added explicit check for empty string ($data === '') alongside the existing false check for more robust handling
• Changed break 2 to single break since we're now only using one loop level

Why

The original code had two issues:

1. The inner loop was effectively a no-op - substr($data, $read) when $read >= strlen($data) returns empty string, causing the loop to execute exactly once
2. $length -= $read was incorrect - should use actual data length since fread() can return fewer bytes than requested

Testing

• All 261 existing tests pass
• Static analysis (phpstan, php-cs-fixer, rector) passes

Closes #27

[s2x]

Review of this PR completed via coder-model (Qwen Code /review):

This PR is a clean, correct simplification of the chunking logic in StreamedBinaryFileResponse::streamContent().

Deterministic checks: PHPStan ✅ | php-cs-fixer ✅ | Rector ✅ | PHPUnit (261 tests) ✅

Why each change is correct:

• Removing the inner while ('' !== \$data) loop — in Symfony's BinaryFileResponse::sendContent() this retries partial fwrite calls, but in a generator model yield delegates I/O to the consumer, so the retry loop is unnecessary
• \$length -= strlen(\$data) fixes the original bug where \$length -= \$read used the requested byte count instead of actual data length from fread()
• \$data === '' check alongside false is sound defensive handling
• break instead of break 2 is correct after removing the nested loop

LGTM ✅ Ready to merge.