fix: cosine-similarity → vector-cosine-similarity naming bug

context-object-render was calling cosince-similarity (undefined) instead
of the actual function name vector-cosine-similarity defined in core-skills.
This would crash at runtime when semantic retrieval was triggered.

lisp/core-context.lisp

@@ -74,7 +74,7 @@ or nil if the heading is not found."
          (obj-vector (memory-object-vector obj))
          (threshold (or semantic-threshold (ignore-errors (read-from-string (uiop:getenv "CONTEXT_SEMANTIC_THRESHOLD"))) 0.75))
          (similarity (if (and foveal-vector obj-vector (not is-foveal))
-                         (cosine-similarity foveal-vector obj-vector)
+                          (vector-cosine-similarity foveal-vector obj-vector)
                          0.0))
          (is-semantically-relevant (>= similarity threshold))
          (should-render (or (<= depth 2) is-foveal is-semantically-relevant))