Add HTTP print API for packing list and sign-off receipt

- core/printing.py: SumatraPDF silent print backend (dry_run, timeout, error capture)
- core/print_document.py: orchestrate generate() + print, per-report paper size, printer fallback
- core/print_api.py: FastAPI POST /api/print + GET /api/health, HTTPBearer auth, English Swagger at /api/docs
- serve.py: uvicorn entrypoint
- config: printers/print/api sections in settings.yaml + core/settings.py
- requirements.txt: add fastapi, uvicorn
- .gitignore: ignore logs/

core/settings.py

@@ -48,11 +48,37 @@ class ReportConfig(BaseModel):
     debug_border: bool = False
 
 
+class PrintersConfig(BaseModel):
+    """打印机配置（MVP：单一默认打印机）"""
+
+    default: str
+
+
+class PrintConfig(BaseModel):
+    """打印后端配置"""
+
+    backend: str = "sumatrapdf"
+    sumatrapdf_path: str = "C:/Program Files/SumatraPDF/SumatraPDF.exe"
+    default_settings: str = "paper=A4,orientation=portrait,color=bw"
+    settings_by_report: dict[str, str] = {}
+
+
+class ApiConfig(BaseModel):
+    """HTTP 打印服务配置"""
+
+    host: str = "0.0.0.0"
+    port: int = 8000
+    token: str = ""
+
+
 class Settings(BaseModel):
     """应用配置"""
 
     database: DatabaseConfig
     report: ReportConfig = ReportConfig()
+    printers: PrintersConfig
+    print: PrintConfig = PrintConfig()
+    api: ApiConfig = ApiConfig()
 
     @property
     def database_url(self) -> URL: