6a6b589ba0
Adds el_black_box (inline asm, +r constraint, memory clobber) and runtime/elbench.el: a growth-curve classifier that gates time AND allocation-count AND allocation-bytes, failing if any exceeds its declared curve. Refusal is a first-class verdict. The classifier REFUSES rather than classifying when the largest measurement is below the floor, or when a series is hard-flat across an 8x input range -- the shape produced when the optimiser deletes the work. Reporting O(1) there would be a confident answer with nothing behind it. Disagreeing ratios report INDETERMINATE rather than a guess. Deviation from DESIGN.md 6.2, stated in the source: uses consecutive ratios on a mandated geometric sweep rather than least-squares over candidate curves. Ratios are directly interpretable on a doubling sweep and need no floating point; the cost is weaker O(n) vs O(n log n) separation, reported as an ambiguous band rather than guessed. Documents the counter scope limit: engram_*.c and libcurl malloc are NOT tracked, so a flat curve over engram/HTTP-dominated work is not evidence of anything. 13 tests prove the classifier against real measured series from fitprobe.el -- including that an accumulator's allocation COUNT is linear while its bytes are quadratic, and that el #132's pure-CPU shape reads FLAT on both allocation signals and is caught only by time.