perf: use sort_unstable_by in extract_rust_idioms

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Co-authored-by: elasticdotventures <35611074+elasticdotventures@users.noreply.github.com>

Author: Copilot

crates/ontology-extractor/src/lib.rs

@@ -84,7 +84,7 @@ impl RustAstExtractor {
             // Sort and dedup by (file, name, classification) so items that share a
             // name in different Rust namespaces (e.g. `struct Foo` and `fn Foo()`)
             // are preserved as distinct entries.
-            terms.sort_by(|left, right| {
+            terms.sort_unstable_by(|left, right| {
                 (left.file.as_str(), left.name.as_str(), left.classification.kind())
                     .cmp(&(right.file.as_str(), right.name.as_str(), right.classification.kind()))
             });