feat: xserial-client with session management, mlua integration, and 238 tests

- Session: background I/O task with SessionHandle for send/read/close/reconfigure
- SessionManager: multi-session collection with aggregated event broadcast
- Config: serializable SessionConfig/PipelineConfig/FramerConfig/DecoderConfig
- Lua: xserial global (open/list_ports/sleep/log) + session userdata API
- RingBuffer: bounded history buffer with pipeline filtering
- Core: added Serialize/Deserialize+Default to Endian/TextEncoding/PlotFormat
- Core: added Send bound to Framer trait for tokio task compatibility
- 238 tests (193 core + 10 config + 7 Lua + 9 session + 18 pipeline + 1 doctest)

crates/xserial-core/src/frame/mod.rs

@@ -13,7 +13,7 @@ pub use crate::protocol::Endian;
 /// arrived.
 ///
 /// [`feed`]: Framer::feed
-pub trait Framer {
+pub trait Framer: Send {
     /// Feed a chunk of newly arrived bytes.
     ///
     /// Any complete frames that can be extracted are returned.  The

crates/xserial-core/src/protocol/mod.rs

@@ -2,10 +2,13 @@ pub mod text;
 pub mod hex;
 pub mod plot;
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
 pub enum Endian {
-    Little,
+    #[default]
     Big,
+    Little,
 }
 
 /// Decoded result from a protocol decoder.

crates/xserial-core/src/protocol/plot.rs

@@ -1,8 +1,9 @@
 use super::{DecodedData, ProtocolDecoder};
 use crate::protocol::Endian;
+use serde::{Deserialize, Serialize};
 
 /// Numeric type of samples in a plot frame.
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
 pub enum SampleType {
     I8,
     U8,
@@ -43,13 +44,11 @@ impl SampleType {
 }
 
 /// Channel layout for multi-channel plot data.
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
 pub enum PlotFormat {
-    /// Interleaved: ch0_s0, ch1_s0, ch0_s1, ch1_s1, ...
+    #[default]
     Interleaved,
-    /// Block: ch0_s0, ch0_s1, ..., ch1_s0, ch1_s1, ...
     Block,
-    /// XY pairs: x0, y0, x1, y1, ... (equivalent to 2 interleaved channels).
     XY,
 }
 

crates/xserial-core/src/protocol/text.rs

@@ -1,14 +1,13 @@
 use super::{DecodedData, ProtocolDecoder};
 
 /// Supported text encodings for the text protocol decoder.
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
 pub enum TextEncoding {
-    /// Standard UTF-8.  Returns `None` from `decode()` on invalid byte sequences.
+    #[default]
     Utf8,
-    /// ISO-8859-1 / Latin-1.  Every byte maps 1:1 to a Unicode code point.
-    /// This encoding never fails.
     Latin1,
-    /// 7-bit ASCII.  Returns `None` from `decode()` if any byte has the high bit set.
     Ascii,
 }