sausage-plugin part 2: import! with typed clients (sausage_interface::client_rs), TCP endpoints with rpc.endpoint, examples

Part 1 fixes: complete stdout writes, buffered stdin, Rust type names
in schemas, enum variant docs, -32603 for serde errors in handlers,
crate docs and modules. End-to-end check of a generated consumer through
a fake core.

sdk/src/lines.rs

@@ -0,0 +1,29 @@
+//! Buffered newline framing shared by stdin and endpoint connections.
+#[cfg(target_os = "wasi")]
+#[derive(Default)]
+pub(crate) struct Lines {
+    bytes: Vec<u8>,
+}
+#[cfg(target_os = "wasi")]
+impl Lines {
+    pub(crate) async fn next(
+        &mut self,
+        input: &mut impl wstd::io::AsyncRead,
+    ) -> std::io::Result<Option<Vec<u8>>> {
+        loop {
+            if let Some(end) = self.bytes.iter().position(|b| *b == b'\n') {
+                return Ok(Some(self.bytes.drain(..=end).collect()));
+            }
+            let mut buffer = [0; 8192];
+            let count = input.read(&mut buffer).await?;
+            if count == 0 {
+                return Ok(if self.bytes.is_empty() {
+                    None
+                } else {
+                    Some(std::mem::take(&mut self.bytes))
+                });
+            }
+            self.bytes.extend_from_slice(&buffer[..count]);
+        }
+    }
+}