CountMinSketchWithHeap still costs at the flat stub — cms-heap wrapper exists but isn't wired up

[milindsrivastava1997]

sketch-bench's `cms-heap` wrapper landed (sketch-bench PR #104), but ASAPQuery's `sketch_bench_key()` (atomic_costs.rs) has no case for `CountMinSketchWithHeap`, so it still always resolves to `AtomicCosts::default()` regardless of params.

Two things needed:

1. `export_atomic_costs.sh` doesn't sweep `cms-heap` yet.
2. Param mismatch: sketch-bench's `CmsHeapParams` is `{rows, cols}` only (`top_k` is compile-time, Frequency/TopK is two registry variants not a field), while ASAPQuery's grid sweeps `{depth, width, heapsize, count_events}`. `heapsize` has no home on the sketch-bench side — stays analytic (`heap_size · avg_key_size`, per Optimizer: param-aware atomic costs from sketch-bench #524) even once CPU costs are wired up. Also unresolved which of the 4 sketch-bench variants (FastPath/RegularPath × Frequency/TopK) matches what ASAPQuery's accumulator actually deploys.

Example: `candidate-gen-dump --atomic-costs ...` shows every `CountMinSketchWithHeap` params row with identical `[stub] mem=1024B insert=1.000e-7s ...`, regardless of depth/width/heapsize.

Part of #524.