=== pyright-0001: CallHierarchyProvider O(C^2) -> O(C) ===

               scale    defective      fixed    speedup
-------------------------------------------------------
  C=  100             0.34ms     0.13ms      2.7x
  C=  500             8.33ms     1.07ms      7.8x
  C= 1000            18.28ms     1.13ms     16.2x
  C= 2000            46.21ms     2.10ms     22.1x
  C= 5000           138.21ms     6.88ms     20.1x

Conclusion: composite-key Map hoist alongside the existing list.
Glue functions with 1000+ call sites hit O(N^2) without this fix.
