chore: Add Chinese README and refactor NPU backend to use Unix domain sockets

- Introduced a new Chinese version of the README (README_CN.md) to provide localized documentation for AgentOS.
- Refactored the NPU bridge to utilize Unix domain sockets instead of HTTP loopback, enhancing security and performance.
- Updated the NPU backend to include a server socket configuration, ensuring proper communication over Unix sockets.
- Modified the Ntex client to support both network and Unix socket transports, improving flexibility in backend communication.
- Adjusted validation logic to enforce the use of Unix sockets for local model endpoints, rejecting loopback HTTP addresses.
- Enhanced error messages and documentation throughout the codebase to clarify the new socket-based architecture.

crates/agentos-cli/src/bin/agentos-npu-bridge.rs

@@ -1,4 +1,4 @@
-use agentos_npu::{LoopbackServerConfig, bridge_chat};
+use agentos_npu::{DEFAULT_NPU_SERVER_SOCKET, UnixSocketServerConfig, bridge_chat};
 use agentos_protocol::ChatRequest;
 use anyhow::{Context, Result, bail};
 use clap::Parser;
@@ -30,9 +30,9 @@ async fn main() -> Result<()> {
         serde_json::from_slice(&input).context("parse agentos.chat.v1 request")?;
     request.validate()?;
     request.parallel_tool_calls = false;
-    let config = LoopbackServerConfig {
-        endpoint: std::env::var("AGENTOS_NPU_SERVER_URL")
-            .unwrap_or_else(|_| "http://127.0.0.1:8031/v1/chat/completions".into()),
+    let config = UnixSocketServerConfig {
+        socket_path: std::env::var_os("AGENTOS_NPU_SERVER_SOCKET")
+            .map_or_else(|| DEFAULT_NPU_SERVER_SOCKET.into(), Into::into),
         model: std::env::var("AGENTOS_NPU_SERVER_MODEL").unwrap_or_else(|_| "agentos-npu".into()),
         timeout: Duration::from_secs(
             std::env::var("AGENTOS_NPU_SERVER_TIMEOUT_S")