* ♻️ Share structural batch upload through common helper
- Merge svg-filters and svg-fills to app.common.render-wasm.svg-derived
- Add serialize-shapes-batch! in common, shared by the sync and chunked
workspace paths
- Add a routing test for the helper and wires the svg-filters test.
AI-assisted-by: muse-spark, GLM 5.3
* 🐛 Derive SVG effects inside single-shape serializer
- Single and batch paths: one svg effect derivation step
owned by shared serializers.
- set-object forwards the derived shape to its host attrs,
and the exporter reads the derived fills, so SVG-attr
fills, blur and shadow render as in the frontend.
- Adds regression test to the exporter.
AI-assisted-by: muse-spark, GLM 5.3, deepseek-flash
