feat: Linux 真实实现层 — 从存根库变为可用生产力工具

新增 _linux_impl.py (800+行):
- LinuxNetwork: 真实IP/接口/DNS/网关/MAC (ip命令+/proc/net)
- LinuxBluetooth: 真实蓝牙状态/扫描/配对/连接 (bluetoothctl)
- LinuxSensors: 真实温度/CPU频率/风扇 (/sys/class/hwmon)
- LinuxAudio: 真实音量控制/静音 (amixer)
- LinuxClipboard: 真实剪贴板读写 (xclip+tkinter回退)
- LinuxPower: 真实CPU/内存/电池 (psutil+/sys/class/power_supply)
- LinuxLocation: 真实IP地理定位 (ip-api.com)
- LinuxNotify: 真实桌面通知 (notify-send)
- LinuxDisplay: 真实屏幕尺寸/截屏/鼠标位置 (xdotool+X11)
- LinuxUIAutomation: 真实点击/输入/按键/滚动 (xdotool)
- LinuxCamera: 真实摄像头拍照 (opencv/V4L2)
- LinuxProcess: 真实进程列表/系统信息/应用管理 (psutil+/proc)
- LinuxShell: 真实命令执行 (subprocess)

改造10+核心类使用Linux真实实现:
- BluetoothAdapter/SensorManager/AudioManager
- ConnectivityManager/WifiManager/TelephonyManager
- LocationManager/PowerManager/BatteryManager/Build
- ActivityManager/Activity/Toast/Display/ClipboardManager
- NotificationManager

15项真实行为测试全部通过:
- 真实IP: 10.60.218.244
- 真实位置: 北京 39.9042, 116.407
- 真实主机名: work-41-vci-g427c
- 真实内核: 5.15.120.byteatom-ck.14
- 真实内存: 1.8GB/3.8GB
- 真实进程列表

android_pyapi/android/content.py

@@ -16,6 +16,12 @@ from .._core import (
     _sdcard_root, _app_data_dir, _package_name,
 )
 
+try:
+    from .._linux_impl import IS_LINUX, LinuxClipboard, LinuxNotify, LinuxLocation, LinuxProcess
+    _USE_LINUX = IS_LINUX
+except ImportError:
+    _USE_LINUX = False
+
 
 # ═══════════════════════════════════════════════════════════════
 # Uri
@@ -466,6 +472,7 @@ class Context(Stub):
     INPUT_METHOD_SERVICE = "input_method"
     CAMERA_SERVICE = "camera"
     BATTERY_SERVICE = "battery"
+    CLIPBOARD_SERVICE = "clipboard"
 
     # Mode 常量
     MODE_PRIVATE = 0x0000
@@ -642,6 +649,8 @@ class Context(Stub):
         if name == Context.BATTERY_SERVICE:
             from .os import BatteryManager
             return BatteryManager()
+        if name == Context.CLIPBOARD_SERVICE:
+            return ClipboardManager()
         return self._services.get(name)
 
     def startService(self, intent: Any) -> Optional[Any]:
@@ -1708,6 +1717,29 @@ class SyncResult(Stub):
         return f"SyncResult({self.stats.numEntries} entries)"
 
 
+# ═══════════════════════════════════════════════════════════════
+# ClipboardManager
+# ═══════════════════════════════════════════════════════════════
+
+class ClipboardManager(Stub):
+    """ClipboardManager — 剪贴板管理器"""
+
+    def getText(self):
+        if _USE_LINUX:
+            return LinuxClipboard.read()
+        return ""
+
+    def setText(self, text):
+        if _USE_LINUX:
+            return LinuxClipboard.write(text)
+        return False
+
+    def hasText(self):
+        if _USE_LINUX:
+            return len(LinuxClipboard.read()) > 0
+        return False
+
+
 # ═══════════════════════════════════════════════════════════════
 # 替换 _core.py 中的 _GlobalContext
 # ═══════════════════════════════════════════════════════════════
@@ -1748,4 +1780,5 @@ __all__ = [
     "DialogInterface",
     "SyncAdapter",
     "SyncResult",
+    "ClipboardManager",
 ]