eureka-state door: drop the unused Display on Refusal

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/eureka-state/src/door.rs

@@ -8,8 +8,6 @@
 //! Both consumers, the `huginn` CLI and the MCP server, admit through this
 //! door and no other.
 
-use std::fmt;
-
 use cultnet_rs::Selection;
 use huginn_mind::eureka_pipeline::PipelineDocument;
 use serde::Serialize;
@@ -31,13 +29,6 @@ impl Refusal {
     }
 }
 
-impl fmt::Display for Refusal {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let (Self::Invalid(detail) | Self::Internal(detail)) = self;
-        f.write_str(detail)
-    }
-}
-
 /// A batch: a JSON array of `{kind, value}` documents, or one such object.
 pub fn documents(text: &str) -> Result<Vec<PipelineDocument>, Refusal> {
     let value = parse(text)?;