Gas Profiler

Separates intrinsic cost — the 21000 base plus 16 gas per non-zero calldata byte, fixed by the protocol before any code runs — from execution, and flags when the payload itself is most of the bill, since no contract optimisation will fix that. Where debug_traceTransaction is available it renders the full call tree with per-call attribution; where the RPC refuses it says so and falls back to receipt-level analysis rather than failing. Full call-tree attribution needs debug_traceTransaction, which most public endpoints do not expose. Where it is unavailable the receipt-level figures shown are still exact, and the app labels which is which rather than presenting an estimate as a measurement.