feat: add Pydantic Settings configuration

src/backend/config.py

@@ -0,0 +1,25 @@
+from pydantic_settings import BaseSettings
+
+
+class Settings(BaseSettings):
+    api_host: str = "0.0.0.0"
+    api_port: int = 8000
+
+    api_key: str
+
+    rate_limit_per_minute: int = 10
+    rate_limit_per_hour: int = 100
+
+    worker_url: str = "http://claude-worker:3001"
+
+    db_path: str = "/data/opus-agent.db"
+
+    claude_model: str = "claude-sonnet-4-6"
+
+    model_config = {
+        "env_file": ".env",
+        "env_file_encoding": "utf-8",
+    }
+
+
+settings = Settings()