plot styles: the CTB/STB model and codec come from the codec crate

Cargo: codec d36331d, kernel 60f086b, graph 74aac56.

The table model and its file codec now live in `codec::plot_style`
(opencadcodec#53) and are re-exported here. What stays is where tables
come from: the plot styles folder, the session registry, the shipped
tables, and saving to disk, as the `PlotStyleTableExt` trait.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/io/pdf_export.rs

@@ -2700,6 +2700,7 @@ pub(crate) fn pdf_stream_text(bytes: &[u8]) -> String {
 
 #[cfg(all(test, not(target_arch = "wasm32")))]
 mod tests {
+    use crate::io::plot_style::PlotStyleTableExt as _;
     use super::*;
 
     fn test_page(wires: Vec<PlotWire>) -> PdfPageInput {