Add arch_svg generator source (meta-device introspection + modular diff + SVG render)

Staged data-flow view for codecs/conv/pipelines (meta-only, memory-safe) with shapes + exposed internals

Forward data-flow view (real I/O shapes per stage) with exposed internal structure

Periodic ×N collapse for heterogeneous module lists (codecs, conv stacks)

Universal module-tree renderer (conv/codec/FFT/SSM) + standardized component colors

Architecture gallery: 435 full renders incl. Mamba/SSM mixers

initial commit