Solution C - Hybrid temp-file streaming:
- ZipPort trait now returns NamedTempFile instead of Vec<u8>
- ZipService writes to a temp file via ZipWriter<std::fs::File> (O(1) RAM)
- Files are read in 64KB stream chunks via get_file_stream() instead of get_file_content()
- HTTP response streams the temp file via ReaderStream (never loads full ZIP in memory)
- Temp file auto-deleted on drop after response completes
- Removed dead imports (HeaderName, HeaderValue, Cursor, Read)
Standardize code formatting across all 173 Rust source files
using rustfmt. No functional changes - purely cosmetic.
This establishes a consistent code style baseline for the
project going forward.