添加PyInstaller打包支持和运行时路径修复

- 创建PyInstaller规范文件和打包脚本
- 修复开发/打包环境路径兼容性问题
- 添加PaddleOCR运行时依赖（opencv-contrib-python, pypdfium2, pyclipper）
- 支持打包后的多进程启动
- 修复图标路径和翻译文件路径
- 清理重复的模型和FFmpeg文件
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/tools/ffmpeg_cli.py

@@ -1,4 +1,5 @@
 import os
+import sys
 import stat
 
 import platform
@@ -21,16 +22,29 @@ class FFmpegCLI:
         return cls._instance
     
     def __init__(self):
-        os.chmod(self.ffmpeg_path, stat.S_IRWXU + stat.S_IRWXG + stat.S_IRWXO)
-        
+        # 设置 FFmpeg 可执行文件权限
+        try:
+            os.chmod(self.ffmpeg_path, stat.S_IRWXU | stat.S_IRGRP | stat.S_IXGRP | stat.S_IROTH | stat.S_IXOTH)
+        except Exception as e:
+            print(f"Warning: Could not set ffmpeg executable permissions: {e}")
+
     @property
     def ffmpeg_path(self):
         system = platform.system()
+
+        # 确保路径正确（打包环境 vs 开发环境）
+        if getattr(sys, 'frozen', False):
+            # 打包环境：BASE_DIR 指向 sys._MEIPASS
+            base_path = os.path.join(BASE_DIR, 'backend')
+        else:
+            # 开发环境：BASE_DIR 已经是项目根目录
+            base_path = BASE_DIR
+
         if system == "Windows":
-            ffmpeg_dir = os.path.join(BASE_DIR, 'ffmpeg', 'win_x64')
+            ffmpeg_dir = os.path.join(base_path, 'ffmpeg', 'win_x64')
             merge_big_file_if_not_exists(ffmpeg_dir, 'ffmpeg.exe')
             return os.path.join(ffmpeg_dir, 'ffmpeg.exe')
         elif system == "Linux":
-            return os.path.join(BASE_DIR, 'ffmpeg',  'linux_x64', 'ffmpeg')
+            return os.path.join(base_path, 'ffmpeg',  'linux_x64', 'ffmpeg')
         else:
-            return os.path.join(BASE_DIR, 'ffmpeg', 'macos', 'ffmpeg')
+            return os.path.join(base_path, 'ffmpeg', 'macos', 'ffmpeg')