chore: scaffold yunke-server

Create pyproject.toml (FastAPI + SQLAlchemy + Playwright + APScheduler +
Redis + cryptography stack), .env.example, app/__init__.py and a
pydantic-settings Settings singleton (get_settings), and a root
.gitignore covering Python, Node, env, IDE and the local media dir.

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

yunke-server/app/config.py

@@ -0,0 +1,30 @@
+from functools import lru_cache
+from pathlib import Path
+
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    """Application settings sourced from environment / .env file."""
+
+    model_config = SettingsConfigDict(
+        env_file=".env",
+        env_file_encoding="utf-8",
+        extra="ignore",
+    )
+
+    yunke_base_url: str = "https://crm2.yunkecn.com"
+    yunke_username: str = ""
+    yunke_password: str = ""
+    db_url: str = "mysql+asyncmy://user:pass@localhost:3306/yunke"
+    redis_url: str = "redis://localhost:6379/0"
+    media_dir: Path = Path("./media")
+    # Fernet key for encrypting stored credentials. Required for real runs;
+    # empty default lets tests construct Settings without a key.
+    encryption_key: str = ""
+
+
+@lru_cache
+def get_settings() -> Settings:
+    """Return the process-wide Settings singleton."""
+    return Settings()