fix(fspy): enable Windows shared memory access from injected DLLs

Create named shared memory mappings that can be opened from child processes
without backing file access. This fixes rust_std tests on Windows where DLLs
injected via Detours need to access the IPC channel.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: wan9chi

crates/fspy_shared/src/ipc/channel/mod.rs

@@ -27,14 +27,17 @@ pub fn channel(capacity: usize) -> io::Result<(ChannelConf, Receiver)> {
     let lock_file_path = temp_dir().join(format!("fspy_ipc_{}.lock", Uuid::new_v4()));
 
     // Initialize the shared memory with a unique id.
+    // Use a named shared memory so it can be opened from other processes.
+    let shm_id = format!("fspy_shm_{}", Uuid::new_v4());
     let shm = ShmemConf::new()
         .size(capacity)
+        .os_id(&shm_id)
         .create()
         .map_err(|err| io::Error::new(io::ErrorKind::Other, err))?;
 
     let conf = ChannelConf {
         lock_file_path: lock_file_path.as_os_str().into(),
-        shm_id: shm.get_os_id().into(),
+        shm_id: shm_id.into(),
         shm_size: capacity,
     };
 
@@ -49,11 +52,13 @@ impl ChannelConf {
     pub fn sender(&self) -> io::Result<Sender> {
         let lock_file = File::open(self.lock_file_path.to_cow_os_str())?;
         lock_file.try_lock_shared()?;
-        let shm = ShmemConf::new()
-            .size(self.shm_size)
-            .os_id(&self.shm_id)
-            .open()
-            .map_err(|err| io::Error::new(io::ErrorKind::Other, err))?;
+        let mut conf = ShmemConf::new().size(self.shm_size).os_id(&self.shm_id);
+        // On Windows, allow opening raw shared memory (without backing file) for DLL injection scenarios
+        #[cfg(target_os = "windows")]
+        {
+            conf = conf.allow_raw(true);
+        }
+        let shm = conf.open().map_err(|err| io::Error::new(io::ErrorKind::Other, err))?;
         let writer = unsafe { ShmWriter::new(shm) };
         Ok(Sender { writer, lock_file, lock_file_path: self.lock_file_path.clone() })
     }