feat(watcher): add macOS autostart support via launchd

internal/watcher/install_mac.go

@@ -0,0 +1,48 @@
+//go:build darwin
+
+package watcher
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+)
+
+func installAutostart() error {
+	exe, err := os.Executable()
+	if err != nil {
+		return err
+	}
+	exe, err = filepath.EvalSymlinks(exe)
+	if err != nil {
+		return err
+	}
+
+	plist := fmt.Sprintf(`<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
+ "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+  <key>Label</key>
+  <string>com.godeez.watch</string>
+  <key>ProgramArguments</key>
+  <array>
+    <string>%s</string>
+    <string>watch</string>
+    <string>run</string>
+  </array>
+  <key>RunAtLoad</key>
+  <true/>
+  <key>KeepAlive</key>
+  <true/>
+</dict>
+</plist>`, exe)
+
+	path := filepath.Join(os.Getenv("HOME"), "Library", "LaunchAgents", "com.godeez.watch.plist")
+	if err := os.WriteFile(path, []byte(plist), 0644); err != nil {
+		return err
+	}
+
+	return exec.Command("launchctl", "load", path).Run()
+}