refactor: remove old .env and config.py files

Remove deprecated app/core/config.py as configuration is now managed
through the new YAML-based config module (app/config/).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/core/config.py

@@ -1,32 +0,0 @@
-from sqlalchemy.engine import URL
-from pydantic_settings import BaseSettings, SettingsConfigDict
-
-
-class Settings(BaseSettings):
-    SQL_SERVER_HOST: str
-    SQL_SERVER_PORT: int = 1433
-    SQL_SERVER_DATABASE: str
-    SQL_SERVER_USERNAME: str
-    SQL_SERVER_PASSWORD: str
-    SQL_SERVER_DRIVER: str = "{ODBC Driver 18 for SQL Server}"
-    SQL_SERVER_TRUST_SERVER_CERTIFICATE: str = "yes"
-
-    @property
-    def database_url(self) -> URL:
-        return URL.create(
-            "mssql+pyodbc",
-            username=self.SQL_SERVER_USERNAME,
-            password=self.SQL_SERVER_PASSWORD,
-            host=self.SQL_SERVER_HOST,
-            port=self.SQL_SERVER_PORT,
-            database=self.SQL_SERVER_DATABASE,
-            query={
-                "driver": self.SQL_SERVER_DRIVER.strip("{}"),
-                "TrustServerCertificate": self.SQL_SERVER_TRUST_SERVER_CERTIFICATE,
-            },
-        )
-
-    model_config = SettingsConfigDict(env_file=".env", extra="ignore")
-
-
-settings = Settings()