Adding Manual connection point to allow undeclared fits

app/api/attachment_points.py

@@ -27,7 +27,7 @@ def _connection_label(ap) -> str:
         return f"{cc.min_in}–{cc.max_in} in"
     if ap.static_connection:
         return f"{ap.static_connection.od_mm} mm OD"
-    return "—"
+    return "Manual"
 
 
 @router.get("", response_model=list[AttachmentPointRead])
@@ -54,10 +54,14 @@ async def create_attachment_point(
         payload.clamp_connection_id,
         payload.static_connection_id,
     ]
-    if sum(v is not None for v in conn_ids) != 1:
+    if sum(v is not None for v in conn_ids) > 1:
         raise HTTPException(
             status_code=400,
-            detail="Exactly one connection (iso_thread, unc_thread, clamp_connection, or static_connection) must be provided.",
+            detail=(
+                "At most one connection (iso_thread, unc_thread, clamp_connection, "
+                "or static_connection) may be provided. Leave all unset for a "
+                "manual attachment point."
+            ),
         )
     ap = await attachment_point_crud.create(db, **payload.model_dump())
     await audit_crud.log(