By: ValentinHirschi <valentin.hirschi@gmail.com>
add live WASM showcases for feynkit, spenso, and idenso Publish six editable FeynKit notebooks covering every component and integrate the shared Spenso + Idenso showcase into both manuals. Build one portable Symbolica community host, bundle offline diagram assets, and wire notebook exports into Just, the docs watcher, and publication. Validation: all six FeynKit browser showcases and both shared showcase pages execute; tensor controls react; native notebook execution, generated stubs, docs-check, builder tests, renderer regression checks, Clippy, and Nix format/workspace-graph checks pass.