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>

backend/app/services/background_tasks.py

@@ -168,24 +168,39 @@ class BackgroundTaskManager:
                 ocr_file.completed_at = datetime.utcnow()
                 ocr_file.processing_time = (ocr_file.completed_at - ocr_file.started_at).total_seconds()
 
-                db.commit()
+                # Commit with retry on connection errors
+                try:
+                    db.commit()
+                except Exception as commit_error:
+                    logger.warning(f"Commit failed, rolling back and retrying: {commit_error}")
+                    db.rollback()
+                    db.refresh(ocr_file)
+                    ocr_file.status = FileStatus.COMPLETED
+                    ocr_file.completed_at = datetime.utcnow()
+                    ocr_file.processing_time = (ocr_file.completed_at - ocr_file.started_at).total_seconds()
+                    db.commit()
 
                 logger.info(f"Successfully processed file {ocr_file.id} ({ocr_file.original_filename})")
                 return True
 
             except Exception as e:
                 logger.error(f"Attempt {attempt + 1}/{self.max_retries + 1} failed for file {ocr_file.id}: {e}")
+                db.rollback()  # Rollback failed transaction
 
                 if attempt < self.max_retries:
                     # Wait before retry
                     time.sleep(self.retry_delay)
                 else:
                     # Final failure
-                    ocr_file.status = FileStatus.FAILED
-                    ocr_file.error_message = f"Failed after {self.max_retries + 1} attempts: {str(e)}"
-                    ocr_file.completed_at = datetime.utcnow()
-                    ocr_file.retry_count = attempt
-                    db.commit()
+                    try:
+                        ocr_file.status = FileStatus.FAILED
+                        ocr_file.error_message = f"Failed after {self.max_retries + 1} attempts: {str(e)}"
+                        ocr_file.completed_at = datetime.utcnow()
+                        ocr_file.retry_count = attempt
+                        db.commit()
+                    except Exception as final_error:
+                        logger.error(f"Failed to update error status: {final_error}")
+                        db.rollback()
                     return False
 
         return False
@@ -375,7 +390,17 @@ def process_batch_files_with_retry(
             batch.status = BatchStatus.FAILED
 
         batch.completed_at = datetime.utcnow()
-        db.commit()
+
+        # Commit with retry on connection errors
+        try:
+            db.commit()
+        except Exception as commit_error:
+            logger.warning(f"Batch commit failed, rolling back and retrying: {commit_error}")
+            db.rollback()
+            batch = db.query(OCRBatch).filter(OCRBatch.id == batch_id).first()
+            if batch:
+                batch.completed_at = datetime.utcnow()
+                db.commit()
 
         logger.info(
             f"Batch {batch_id} processing complete: "
@@ -384,6 +409,7 @@ def process_batch_files_with_retry(
 
     except Exception as e:
         logger.error(f"Fatal error processing batch {batch_id}: {e}")
+        db.rollback()  # Rollback any failed transaction
         try:
             batch = db.query(OCRBatch).filter(OCRBatch.id == batch_id).first()
             if batch:
@@ -392,3 +418,4 @@ def process_batch_files_with_retry(
                 db.commit()
         except Exception as commit_error:
             logger.error(f"Error updating batch status: {commit_error}")
+            db.rollback()

backend/app/services/office_converter.py

@@ -42,14 +42,16 @@ class OfficeConverter:
     def _verify_libreoffice(self):
         """Verify LibreOffice is installed and accessible"""
         if not Path(self.libreoffice_path).exists():
-            # Try alternative path for Homebrew installation
+            # Try alternative path (system-wide installation)
             alt_path = shutil.which("soffice")
             if alt_path:
                 self.libreoffice_path = alt_path
                 logger.info(f"Using LibreOffice at: {alt_path}")
             else:
                 raise OfficeConverterError(
-                    "LibreOffice not found. Please install LibreOffice: brew install libreoffice"
+                    "LibreOffice not found. Please install LibreOffice:\n"
+                    "  Ubuntu/Debian: sudo apt install -y libreoffice-writer libreoffice-impress libreoffice-core-nogui\n"
+                    "  macOS: brew install libreoffice"
                 )
 
     def is_office_document(self, file_path: Path) -> bool: