9c9026e7ca
Replace Vec<Vec<f32>> with flat stack arrays in ldpc_decode (~114KB), convert 19+ Vec allocations to stack arrays in osd174_91, eliminate per-call temp Vec in nextpat91 via in-place mutation, and replace norm() with norm_sqr() in bitmetrics hot loop (~5.4M calls/frame). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com> Signed-off-by: Stan Grams <sjg@haxx.space>