feat: rework to use next and host from single dockerfile

mta_sign_server/config/schemas.py

@@ -0,0 +1,14 @@
+from pydantic import BaseModel
+
+
+class Station(BaseModel):
+    id: str
+    name: str
+
+
+class StationsResponse(BaseModel):
+    stations: list[Station]
+
+
+class LinesResponse(BaseModel):
+    lines: list[str]