feat(web): self-host Japanese font and load on-demand without external CDN

- Bundle BIZ UDPGothic Regular (SIL OFL 1.1) exclusively in solvecraft-web dist

- Remove external jsDelivr CDN fallback; fetch font solely from same-origin ./fonts/

- Fetch Japanese font on-demand only when UI language is set to Japanese

- Gracefully fall back to English UI on fetch failure to prevent tofu glyphs

- Update ATTRIBUTION.md, NOTICE, and THIRD-PARTY-LICENSES.txt

ATTRIBUTION.md

@@ -26,6 +26,7 @@ Generated-in-code assets are original and have no file to list:
 | docs/book/src/generated/revolve.png | SolveCraft contributors | rendered by `cargo xtask book` (`solvecraft-cli snapshot docs/book/scripts/revolve.json`; gitignored) | MIT OR Apache-2.0 |
 | docs/book/src/generated/sheet-metal.png | SolveCraft contributors | rendered by `cargo xtask book` (`solvecraft-cli snapshot docs/book/scripts/sheet-metal.json`; gitignored) | MIT OR Apache-2.0 |
 | crates/sketch/fonts/LiberationSans-Regular.ttf | Red Hat, Inc. (Liberation Fonts 2.x; digitized data Google) | https://github.com/liberationfonts (Debian fonts-liberation), unmodified; licence text in crates/sketch/fonts/OFL.txt; used for sketch Text outlines | SIL OFL 1.1 |
+| apps/solvecraft-web/fonts/BIZUDPGothic-Regular.ttf | The BIZ UDGothic Project Authors | https://github.com/googlefonts/morisawa-biz-ud-gothic (Google Fonts), unmodified; licence text in apps/solvecraft-web/fonts/OFL.txt; used for web UI Japanese font | SIL OFL 1.1 |
 
 ## Code adapted from sibling projects