feat: migrate to WSL Ubuntu native development environment

從 Docker/macOS+Conda 部署遷移到 WSL2 Ubuntu 原生開發環境

主要變更：
- 移除所有 Docker 相關配置檔案 (Dockerfile, docker-compose.yml, .dockerignore 等)
- 移除 macOS/Conda 設置腳本 (SETUP.md, setup_conda.sh)
- 新增 WSL Ubuntu 自動化環境設置腳本 (setup_dev_env.sh)
- 新增後端/前端快速啟動腳本 (start_backend.sh, start_frontend.sh)
- 統一開發端口配置 (backend: 8000, frontend: 5173)
- 改進資料庫連接穩定性（連接池、超時設置、重試機制）
- 更新專案文檔以反映當前 WSL 開發環境

Technical improvements:
- Database connection pooling with health checks and auto-reconnection
- Retry logic for long-running OCR tasks to prevent DB timeouts
- Extended JWT token expiration to 24 hours
- Support for Office documents (pptx, docx) via LibreOffice headless
- Comprehensive system dependency installation in single script

Environment:
- OS: WSL2 Ubuntu 24.04
- Python: 3.12 (venv)
- Node.js: 24.x LTS (nvm)
- Backend Port: 8000
- Frontend Port: 5173

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

start_frontend.sh

@@ -0,0 +1,40 @@
+#!/bin/bash
+# Tool_OCR - 前端開發服務器啟動腳本
+
+set -e
+
+# 顏色定義
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+RED='\033[0;31m'
+NC='\033[0m' # No Color
+
+echo -e "${YELLOW}正在啟動 Tool_OCR 前端開發服務器...${NC}"
+echo ""
+
+# 檢查 node_modules
+if [ ! -d "frontend/node_modules" ]; then
+    echo -e "${RED}錯誤: 未找到 node_modules${NC}"
+    echo "請先運行: ./setup_dev_env.sh"
+    exit 1
+fi
+
+# 載入 nvm
+export NVM_DIR="$HOME/.nvm"
+[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"
+
+# 進入前端目錄
+cd frontend
+
+# 啟動前端服務器
+echo ""
+echo -e "${GREEN}================================${NC}"
+echo -e "${GREEN}前端服務器啟動中...${NC}"
+echo -e "${GREEN}================================${NC}"
+echo ""
+echo "前端界面: http://localhost:5173"
+echo ""
+echo "按 Ctrl+C 停止服務器"
+echo ""
+
+npm run dev