Seeds: robust default fee type lookup; no fee type overwrite on re-run

Bootstrap: filter default fee type by name and interval (yearly).
Dev: do not send membership_fee_type_id in member upsert; set only
via update when nil so re-runs do not overwrite existing assignments.

priv/repo/seeds_bootstrap.exs

@@ -55,9 +55,10 @@ for attrs <- fee_type_configs do
 end
 
 # Resolve default fee type (Standard, 120€ yearly) for settings
+# Filter by name and interval to avoid ambiguity if multiple "Standard" types exist
 default_fee_type =
   Mv.MembershipFees.MembershipFeeType
-  |> Ash.Query.filter(name == "Standard")
+  |> Ash.Query.filter(name == "Standard" and interval == :yearly)
   |> Ash.read_one!(authorize?: false, domain: Mv.MembershipFees)
 
 # 2. Custom fields (authorize?: false for bootstrap)