fix(compact): cross-platform statvfs type compatibility

Cast f_bavail and f_frsize to u64 for macOS compatibility.
On macOS these are u32, while on Linux they are u64.

Author: echobt

src/cortex-compact/src/auto_compaction/utils.rs

@@ -20,6 +20,7 @@ pub fn chrono_timestamp() -> String {
 
 /// Estimate available disk space in bytes (platform-specific).
 #[cfg(unix)]
+#[allow(clippy::unnecessary_cast)] // Cast needed for cross-platform: macOS has u32, Linux has u64
 pub fn available_disk_space(path: &Path) -> io::Result<u64> {
     use std::ffi::CString;
     use std::mem::MaybeUninit;
@@ -31,7 +32,8 @@ pub fn available_disk_space(path: &Path) -> io::Result<u64> {
         let mut statvfs = MaybeUninit::<libc::statvfs>::uninit();
         if libc::statvfs(c_path.as_ptr(), statvfs.as_mut_ptr()) == 0 {
             let statvfs = statvfs.assume_init();
-            Ok(statvfs.f_bavail * statvfs.f_frsize)
+            // Cast to u64 for cross-platform compatibility (macOS has u32 for f_bavail)
+            Ok((statvfs.f_bavail as u64) * (statvfs.f_frsize as u64))
         } else {
             Err(io::Error::last_os_error())
         }