Remove insight experimental code

Also, downgrade LLM for commands to mini. It's much cheaper and I only upgraded because of the
interpretation complexities that the insight command introduced.

We are implementing a much better approach with Ask.

app/models/command/parser.rb

@@ -55,8 +55,6 @@ class Command::Parser
         Command::Consider.new(card_ids: cards.ids)
       when "/do"
         Command::Do.new(card_ids: cards.ids)
-      when "/insight"
-        Command::GetInsight.new(query: combined_arguments, card_ids: cards.ids, params: filter.as_params)
       when "/add"
         Command::AddCard.new(card_title: combined_arguments, collection_id: guess_collection&.id)
       when "/search"