refactor: 重构为纯云端版本，移除所有本地ML库依赖

重大更改：
1. requirements.txt - 移除 paddleocr/paddlepaddle，使用纯 API 版本
2. src/core/ocr.py - 完全重写
   - 移除 PaddleOCREngine 和 ensure_paddleocr()
   - 移除 numpy 依赖（不再需要）
   - 实现完整的 CloudOCREngine
   - 支持百度/腾讯/阿里云 OCR API
   - 添加自定义 API 支持
3. src/config/settings.py - 简化 OCR 配置
   - OCRMode 枚举仅保留 CLOUD
   - OCRConfig 添加 provider 字段
4. src/core/__init__.py - 移除 PaddleOCREngine 导出
5. src/gui/main_window.py - 移除 ensure_paddleocr 导入
6. build.bat/build.sh - 简化构建参数
   - 移除所有 ML 库的 --exclude-module
   - 移除 pyi_hooks 依赖
   - 添加 openai/anthropic hidden-import

测试：
- ✓ 所有核心模块导入成功
- ✓ 没有 PaddleOCR 相关错误

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

build.bat

@@ -1,58 +1,52 @@
 @echo off
 REM ================================
-REM CutThenThink Windows Build Script
+REM CutThenThink Windows Build Script - Cloud Only Version
 REM ================================
+REM 纯云端版本 - 无需本地 ML 库
 
-REM Change to project directory
 cd /d "%~dp0"
 
+echo ========================================
+echo CutThenThink 纯云端版本构建
+echo ========================================
+echo.
+echo 特点：
+echo - OCR 使用云端 API
+echo - AI 使用 API (OpenAI/Anthropic)
+echo - 无需任何本地 ML 库
+echo ========================================
+echo.
+
 REM Check Python
-echo Checking Python...
+echo [1/4] 检查 Python...
 python --version 2>nul
 if errorlevel 1 (
-    echo Python not found. Please install Python 3.8+
+    echo 错误: 未找到 Python
     pause
     exit /b 1
 )
 
-REM Get Python version
-for /f "tokens=2" %%i in ('python --version 2^>^&1') do set PYVER=%%i
-echo Detected Python %PYVER%
-
 echo.
-echo 1/5. Installing PyInstaller...
+echo [2/4] 安装核心依赖...
 python -m pip install --user pyinstaller 2>nul
-
-echo.
-echo 2/5. Installing dependencies (compatible with Python 3.13)...
-REM Use SQLAlchemy 2.0.36+ for Python 3.13 compatibility
-python -m pip install --user "sqlalchemy>=2.0.36" 2>nul
 python -m pip install --user "PyQt6>=6.7.0" 2>nul
-python -m pip install --user pyyaml 2>nul
-python -m pip install --user requests 2>nul
-python -m pip install --user pillow 2>nul
-python -m pip install --user pyperclip 2>nul
-
-REM Install build dependencies
-python -m pip install --user setuptools 2>nul
+python -m pip install --user "SQLAlchemy>=2.0.36" 2>nul
+python -m pip install --user openai anthropic 2>nul
+python -m pip install --user requests pyyaml pillow pyperclip 2>nul
 
 echo.
-echo 3/5. Cleaning previous build...
+echo [3/4] 清理旧的构建...
 if exist build rmdir /s /q build
 if exist dist rmdir /s /q dist
 
 echo.
-echo 4/5. Building executable...
-echo NOTE: Using custom hooks to exclude heavy ML libraries that cause Python 3.13 issues
-echo These will be installed dynamically at runtime if needed
+echo [4/4] 开始构建...
 python -m PyInstaller ^
     --noconfirm ^
     --name "CutThenThink" ^
     --windowed ^
     --onefile ^
     --add-data "src:src" ^
-    --runtime-hook=pyi_hooks/pyi_rth_ignore_torch.py ^
-    --additional-hooks-dir=pyi_hooks ^
     --hidden-import=PyQt6.QtCore ^
     --hidden-import=PyQt6.QtGui ^
     --hidden-import=PyQt6.QtWidgets ^
@@ -60,35 +54,18 @@ python -m PyInstaller ^
     --hidden-import=sqlalchemy.orm ^
     --hidden-import=PIL ^
     --hidden-import=PIL.Image ^
-    --hidden-import=PIL.ImageEnhance ^
-    --hidden-import=PIL.ImageFilter ^
-    --hidden-import=numpy ^
     --hidden-import=pyperclip ^
-    --hidden-import=tkinter ^
-    --hidden-import=tkinter.ttk ^
-    --hidden-import=tkinter.scrolledtext ^
-    --hidden-import=tkinter.messagebox ^
     --hidden-import=yaml ^
     --hidden-import=requests ^
+    --hidden-import=openai ^
+    --hidden-import=anthropic ^
     --collect-all pyqt6 ^
-    --exclude-module=torch ^
-    --exclude-module=transformers ^
-    --exclude-module=tensorflow ^
-    --exclude-module=onnx ^
-    --exclude-module=onnxruntime ^
-    --exclude-module=sentencepiece ^
-    --exclude-module=tokenizers ^
-    --exclude-module=diffusers ^
-    --exclude-module=accelerate ^
-    --exclude-module=datasets ^
-    --exclude-module=huggingface_hub ^
-    --exclude-module=safetensors ^
     src/main.py
 
 if errorlevel 1 (
     echo.
     echo ================================
-    echo Build Failed!
+    echo 构建失败！
     echo ================================
     pause
     exit /b 1
@@ -96,11 +73,12 @@ if errorlevel 1 (
 
 echo.
 echo ================================
-echo Build Complete!
-echo Executable: dist\CutThenThink.exe
-echo File size: ~30-50 MB
+echo 构建成功！
 echo ================================
+echo 可执行文件: dist\CutThenThink.exe
 echo.
-echo On first run, app will auto-download and install PaddleOCR.
+echo 首次运行请配置：
+echo - AI API Key (OpenAI/Anthropic)
+echo - 云端 OCR API
 echo.
 pause