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>

frontend/src/services/api.ts

@@ -19,10 +19,10 @@ import type {
 /**
  * API Client Configuration
  * - In Docker: VITE_API_BASE_URL is empty string, use relative path
- * - In development: Use VITE_API_BASE_URL from .env or default to localhost:12015
+ * - In development: Use VITE_API_BASE_URL from .env or default to localhost:8000
  */
 const envApiBaseUrl = import.meta.env.VITE_API_BASE_URL
-const API_BASE_URL = envApiBaseUrl !== undefined ? envApiBaseUrl : 'http://localhost:12015'
+const API_BASE_URL = envApiBaseUrl !== undefined ? envApiBaseUrl : 'http://localhost:8000'
 const API_VERSION = 'v1'
 
 class ApiClient {