Create add_user rout

And fix some bullshit

app/schemas/base_schemas.py

@@ -0,0 +1,17 @@
+from pydantic import BaseModel
+
+
+class User(BaseModel):
+    user_id: int
+    username: str
+
+    first_name: str
+    last_name: str
+    photo_url: str
+
+    activity: int = 0
+    liked_post_ids: list[int] = list()
+    disliked_post_ids: list[int] = list()
+    comments_ids: list[int] = list()
+
+    registration_date: str