Fix corrupt PlayfairDisplay-Bold.ttf (was HTML), mirror to hf_space

The cream-serif comparison theme was already implemented (theme
dict, config field, render._fonts() branch, CLI flag, customizer
dropdown all in place from previous work). The blocker was a
corrupt PlayfairDisplay-Bold.ttf file — the previous download
saved an HTML redirect page instead of the TTF.

- assets/fonts/PlayfairDisplay-Bold.ttf: re-downloaded from the
actual raw.githubusercontent.com URL for the variable font
(300724 bytes, valid TrueType with DSIG signature).
- hf_space/assets/fonts/PlayfairDisplay-Bold.ttf: added a copy
for HF Space deployments.

Verified both themes render correctly end-to-end:
- python -m comparison --input jordan_vs_lebron.csv --comparison-theme cream-serif
- python -m comparison --input jordan_vs_lebron.csv --comparison-theme dark

No src/bar_race/ files modified. No src/comparison/ code changes
needed — everything was already in place.

https://claude.ai/code/session_01PzSuVpJ1KAsAPLLEw75nZS

assets/fonts/PlayfairDisplay-Bold.ttf

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:c40f2293766a503bc70cce9e512ef844a4ccb7cbcde792fe2ea31d191917d8d6
+size 300724