feat: 新增测试 runtime

apps/hello/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "hello"
+version = "0.1.0"

apps/hello/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "hello"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

apps/hello/src/main.rs

@@ -0,0 +1,9 @@
+fn main() {
+    println!("Hello from OpenWrt (ARMhf)!");
+    println!("System information (via /proc/version):");
+    if let Ok(version) = std::fs::read_to_string("/proc/version") {
+        println!("{}", version);
+    } else {
+        println!("Could not read /proc/version (running in simulation?)");
+    }
+}