fix: remove unused WhaleRoute import, allow dead_code on for_model_effort

- model_picker.rs no longer directly references WhaleRoute (uses
  WHALE_ROUTES.iter().position() instead of WhaleRoute::for_model_effort)
- whale_routes.rs: for_model_effort is only used in tests; add
  #[allow(dead_code)] to suppress -D warnings in release builds

crates/tui/src/tui/model_picker.rs

@@ -24,7 +24,7 @@ use ratatui::{
 use crate::palette;
 use crate::tui::app::{App, ReasoningEffort};
 use crate::tui::views::{ModalKind, ModalView, ViewAction, ViewEvent};
-use crate::tui::whale_routes::{WHALE_ROUTES, WhaleRoute};
+use crate::tui::whale_routes::WHALE_ROUTES;
 
 /// Models the picker exposes by default. Kept short on purpose — power
 /// users can still type `/model <id>` for anything else.

crates/tui/src/tui/whale_routes.rs

@@ -93,6 +93,7 @@ impl WhaleRoute {
     /// Look up the whale route for a given model id and reasoning effort.
     /// Returns `None` for non-DeepSeek models or unrecognized combinations.
     #[must_use]
+    #[allow(dead_code)]
     pub fn for_model_effort(model: &str, effort: ReasoningEffort) -> Option<&'static WhaleRoute> {
         WHALE_ROUTES
             .iter()