Notebook cards now show schematic SVG thumbnails (on Mims green background)
and description snippets extracted from the first markdown cell. The backend
extracts both from already-loaded notebook data at zero additional I/O cost.
New ResistorColorGuide section between the pipeline strip and featured
notebooks explains the 4-band color code with an annotated zigzag diagram
and reference table using the same BAND_HEX colors from the schematic renderer.
Also switches docker-compose.dev.yml from direct port mapping to Caddy labels,
matching the production routing pattern and avoiding port conflicts.
Ryan Malloy
2ddc08cd3a