Fixed compilation errors:
- Added <dirent.h> include to file_system.h for DIR type on Linux
- Replaced xxx placeholder in chunk_server.c with actual chunks_dir path
using state->store.path
Fixed several bugs in the DirectoryScanner implementation:
Windows fixes:
- Fixed snprintf call missing buffer size parameter
- Fixed FindFirstFileA to use pattern (with wildcard) instead of path
- Changed sys_GetLastError() to GetLastError()
- Added scanner->first = false after using first result
- Removed TODO comment from cFileName usage (it's the correct field)
Linux fixes:
- Fixed typo: sys_reddir → sys_readdir
- Added missing 'done' field to DirectoryScanner struct
- Initialize scanner->done = false on successful opendir
- Fixed return value when scanner->done (should return 1, not -1)