Add: Metadata for observability (#508)

---------

Co-authored-by: Mikhail Bautin <[email protected]>

Author: mbautin

include/usearch/index.hpp

@@ -3175,6 +3175,18 @@ class index_gt {
 
     std::size_t memory_usage_per_node(level_t level) const noexcept { return node_bytes_(level); }
 
+    double inverse_log_connectivity() const {
+        return pre_.inverse_log_connectivity;
+    }
+
+    std::size_t neighbors_base_bytes() const {
+        return pre_.neighbors_base_bytes;
+    }
+
+    std::size_t neighbors_bytes() const {
+        return pre_.neighbors_bytes;
+    }
+
 #if defined(USEARCH_USE_PRAGMA_REGION)
 #pragma endregion
 

include/usearch/index_dense.hpp

@@ -693,6 +693,9 @@ class index_dense_gt {
     std::size_t max_level() const { return typed_->max_level(); }
     index_dense_config_t const& config() const { return config_; }
     index_limits_t const& limits() const { return typed_->limits(); }
+    double inverse_log_connectivity() const { return typed_->inverse_log_connectivity(); }
+    std::size_t neighbors_base_bytes() const { return typed_->neighbors_base_bytes(); }
+    std::size_t neighbors_bytes() const { return typed_->neighbors_bytes(); }
     bool multi() const { return config_.multi; }
     std::size_t currently_available_threads() const {
         std::unique_lock<std::mutex> available_threads_lock(available_threads_mutex_);