Anvil v1.0.0 -- Arduino build tool with HAL and test scaffolding

Single-binary CLI that scaffolds testable Arduino projects, compiles,
uploads, and monitors serial output. Templates embed a hardware
abstraction layer, Google Mock infrastructure, and CMake-based host
tests so application logic can be verified without hardware.

Commands: new, doctor, setup, devices, build, upload, monitor
39 Rust tests (21 unit, 18 integration)
Cross-platform: Linux and Windows

src/commands/devices.rs

@@ -0,0 +1,67 @@
+use anyhow::Result;
+use colored::*;
+
+use crate::board;
+
+pub fn scan_devices() -> Result<()> {
+    println!(
+        "{}",
+        "=== Connected Serial Devices ===".bold()
+    );
+    println!();
+
+    let ports = board::list_ports();
+    board::print_port_details(&ports);
+
+    // Also run arduino-cli board list for cross-reference
+    if let Some(cli_path) = board::find_arduino_cli() {
+        println!();
+        println!(
+            "{}",
+            "=== arduino-cli Board Detection ===".bold()
+        );
+        println!();
+
+        let output = std::process::Command::new(&cli_path)
+            .args(["board", "list"])
+            .output();
+
+        match output {
+            Ok(out) if out.status.success() => {
+                let stdout = String::from_utf8_lossy(&out.stdout);
+                for line in stdout.lines() {
+                    println!("  {}", line);
+                }
+            }
+            _ => {
+                eprintln!(
+                    "  {}",
+                    "arduino-cli board list failed (is the core installed?)"
+                        .yellow()
+                );
+            }
+        }
+    } else {
+        println!();
+        eprintln!(
+            "  {}",
+            "arduino-cli not found -- run 'anvil setup' first".yellow()
+        );
+    }
+
+    println!();
+
+    if ports.is_empty() {
+        println!("{}", "Troubleshooting:".bright_yellow().bold());
+        println!("  - Try a different USB cable (many are charge-only)");
+        println!("  - Try a different USB port");
+        #[cfg(target_os = "linux")]
+        {
+            println!("  - Check kernel log: dmesg | tail -20");
+            println!("  - Check USB bus: lsusb | grep -i -E 'ch34|arduino|1a86|2341'");
+        }
+        println!();
+    }
+
+    Ok(())
+}