the browser learns the layout tree

open   by a73x

muxweb renders wall tiles in its own DOM arrangement and never sees the CLI wall's layout tree. layout.zig is pure layer-1 Zig (wasm-compilable — the one-layout-core move, like replica) and the hub already serves wall state over HTTP (/tiles). Follow-up to multipane chunk 3: serve the layout sidecar beside /tiles and render the same tree as CSS panes in the browser; possibly edit it there. See docs/superpowers/specs/2026-08-24-layout-persistence-design.md (web hub out of scope note).