feat: add validation for minimum length on various fields and update type definitions

backend/app/schemas/gateways.py

@@ -1,8 +1,10 @@
 from __future__ import annotations
 
 from datetime import datetime
+from typing import Any
 from uuid import UUID
 
+from pydantic import field_validator
 from sqlmodel import SQLModel
 
 
@@ -17,6 +19,16 @@ class GatewayBase(SQLModel):
 class GatewayCreate(GatewayBase):
     token: str | None = None
 
+    @field_validator("token", mode="before")
+    @classmethod
+    def normalize_token(cls, value: Any) -> Any:
+        if value is None:
+            return None
+        if isinstance(value, str):
+            value = value.strip()
+            return value or None
+        return value
+
 
 class GatewayUpdate(SQLModel):
     name: str | None = None
@@ -26,6 +38,16 @@ class GatewayUpdate(SQLModel):
     workspace_root: str | None = None
     skyll_enabled: bool | None = None
 
+    @field_validator("token", mode="before")
+    @classmethod
+    def normalize_token(cls, value: Any) -> Any:
+        if value is None:
+            return None
+        if isinstance(value, str):
+            value = value.strip()
+            return value or None
+        return value
+
 
 class GatewayRead(GatewayBase):
     id: UUID