feat: bell-tower favicon, lfx-clean flows, branded HTML mail

backend/app/flows/input_schema.py

@@ -96,6 +96,11 @@ def _field_schema(name: str, field: dict) -> tuple[dict, dict]:
 
     value = field.get("value")
     if value is not None:
+        # Whitespace-only string values are the flow generator's sentinel
+        # for "required, filled at runtime" (see make_flow_fixtures.py) —
+        # not a real default for the web form.
+        if isinstance(value, str) and not value.strip():
+            return prop, ui
         # A default outside its enum would fail validation on touch.
         enum = prop.get("enum")
         if not (enum is not None and value not in enum):