fix(pdf): Flate-compress the exported PDF streams

printpdf 0.9's `PdfSaveOptions::optimize` is a no-op — its `doc.compress()`
call is commented out — so every page's content stream (megabytes of vector
operators for a CAD sheet) was written uncompressed: a 16-sheet drawing set
exported as 280 MB. Serialise through `printpdf::to_lopdf_doc` and run
lopdf's `compress()` before writing; the same export is now 49 MB and
readers see ordinary FlateDecode streams.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

Cargo.lock

@@ -38,6 +38,7 @@ dependencies = [
  "js-sys",
  "libloading",
  "log",
+ "lopdf",
  "lyon_tessellation",
  "meshopt",
  "naga 27.0.3",