feat: implement ADB wrapper and device management backend

Adds full ADB client, device manager, static DeviceInfo fetcher, and
live DeviceLiveStats poller. Exposes ListDevices, ConnectDevice,
DisconnectDevice, GetDeviceInfo, GetDeviceLiveStats as Wails-bound
methods with a 1s devices:changed event loop. Bundles ADB binary
infrastructure via //go:embed all:bin with runtime fallback chain.

desktop/internal/adbembed/embed.go

@@ -0,0 +1,71 @@
+package adbembed
+
+import (
+	"embed"
+	"fmt"
+	"os"
+	"path/filepath"
+	"runtime"
+)
+
+//go:embed all:bin
+var binFS embed.FS
+
+// Resolve returns the path to a usable adb binary.
+// Order: embedded binary → ANDROID_HOME → PATH.
+func Resolve() (string, error) {
+	if path, err := extractEmbedded(); err == nil {
+		return path, nil
+	}
+	return findOnSystem()
+}
+
+func extractEmbedded() (string, error) {
+	name := embeddedName()
+	data, err := binFS.ReadFile("bin/" + name)
+	if err != nil || len(data) < 1024 {
+		return "", fmt.Errorf("no embedded binary")
+	}
+
+	cacheDir, err := os.UserCacheDir()
+	if err != nil {
+		return "", err
+	}
+	dir := filepath.Join(cacheDir, "droidscope", "adb")
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return "", err
+	}
+
+	dest := filepath.Join(dir, adbExeName())
+	if err := os.WriteFile(dest, data, 0755); err != nil {
+		return "", err
+	}
+	return dest, nil
+}
+
+func findOnSystem() (string, error) {
+	if home := os.Getenv("ANDROID_HOME"); home != "" {
+		candidate := filepath.Join(home, "platform-tools", adbExeName())
+		if _, err := os.Stat(candidate); err == nil {
+			return candidate, nil
+		}
+	}
+	// Fall back to PATH
+	return findInPath()
+}
+
+func embeddedName() string {
+	os_ := runtime.GOOS
+	arch := runtime.GOARCH
+	if os_ == "windows" {
+		return fmt.Sprintf("adb-%s-%s.exe", os_, arch)
+	}
+	return fmt.Sprintf("adb-%s-%s", os_, arch)
+}
+
+func adbExeName() string {
+	if runtime.GOOS == "windows" {
+		return "adb.exe"
+	}
+	return "adb"
+}

desktop/internal/adbembed/path_unix.go

@@ -0,0 +1,11 @@
+//go:build !windows
+
+package adbembed
+
+import (
+	"os/exec"
+)
+
+func findInPath() (string, error) {
+	return exec.LookPath("adb")
+}

desktop/internal/adbembed/path_windows.go

@@ -0,0 +1,11 @@
+//go:build windows
+
+package adbembed
+
+import (
+	"os/exec"
+)
+
+func findInPath() (string, error) {
+	return exec.LookPath("adb.exe")
+}