Warn when skill catalogs exceed their context budget (#34997)

## Why

Skill catalog rendering can shorten descriptions or omit enabled skills to fit
the model context budget. Surface these reductions so users know when the
model-visible catalog has lost detail.

## What changed

- Emit a warning with the omitted skill count whenever entries do not fit.
- Warn when description shortening averages more than 100 characters per skill.
- Deduplicate executor catalog warnings across repeated world-state builds in a
  turn.

## Testing

- Cover the description-shortening threshold and omission warning text.
- Verify warnings through extension and production-turn catalogs, including
  per-turn deduplication.

GitOrigin-RevId: bd7fc3482e5dfd8c79072f772a2f54aa502478d9

codex-rs/ext/skills/src/state.rs

@@ -1,4 +1,5 @@
 use std::collections::HashMap;
+use std::collections::HashSet;
 use std::future::Future;
 use std::sync::Arc;
 use std::sync::Mutex;
@@ -337,6 +338,18 @@ impl OrchestratorResourceCache {
     }
 }
 
+#[derive(Default)]
+pub(crate) struct EmittedCatalogBudgetWarnings(Mutex<HashSet<String>>);
+
+impl EmittedCatalogBudgetWarnings {
+    pub(crate) fn insert(&self, warning: &str) -> bool {
+        self.0
+            .lock()
+            .unwrap_or_else(std::sync::PoisonError::into_inner)
+            .insert(warning.to_string())
+    }
+}
+
 #[derive(Clone, Debug, Default, PartialEq, Eq)]
 pub(crate) struct SkillsTurnState {
     pub(crate) catalog: SkillCatalog,