v1.8.0: the settled release

The maturity sprint closes. Since the completion release: red-team round eight (seven attacks on the fluids, machinery, jelly and decompose surface, all held), the fuzzer now fills pools and tears nets under all four promises on every seed and cell, a weekly scheduled CI run of the full matrix plus a 300k-step soak guards against toolchain drift, the 1.x API surface is frozen with its format contract written into the guide, cmake install / find_package / pkg-config all hand consumers the same bits (verified end to end), tag pushes attach prebuilt static libraries for Linux, Windows and macOS (this release is the first to carry them, built by the new pipeline), the testbed's goo scene shows the whole particle palette in color, samples/minimal takes a newcomer from install to a hash-verified rollback in ten minutes, and particles answer region queries under the standard enumeration contract. Wire v30, snapshot v31, 16 gated determinism lines across 9 CI cells and 3 instruction sets.