feat: add HttpUrlStr shared URL validator

surfsense_backend/app/capabilities/core/validation.py

@@ -0,0 +1,24 @@
+"""Shared Pydantic field types for capability I/O schemas."""
+
+from __future__ import annotations
+
+from typing import Annotated
+from urllib.parse import urlsplit
+
+import validators
+from pydantic import AfterValidator
+from pydantic_core import PydanticCustomError
+
+_HTTP_SCHEMES = frozenset({"http", "https"})
+
+
+def _validate_http_url(value: str) -> str:
+    """Accept only well-formed http(s) URLs, returned trimmed and unchanged."""
+    url = value.strip()
+    if not validators.url(url) or urlsplit(url).scheme.lower() not in _HTTP_SCHEMES:
+        raise PydanticCustomError("http_url", "must be a valid http(s) URL")
+    return url
+
+
+HttpUrlStr = Annotated[str, AfterValidator(_validate_http_url)]
+"""A request URL validated as http(s) and kept as ``str`` (no normalization)."""