Add hash routing and Dota 2 logo to relations preview.
- New web/relations/router.js (parseHash/serializeHash/installRouter):
top tabs, hero + detail sub-tab, item, patch version, tag filters and
search query all sync to URL (#/heroes/axe/core, ?tags=...&q=...);
pushState for discrete picks, replaceState for debounced search.
- export_relations_site.py copies router.js so static export deep-links.
- Header shows dota2_logo.png + title, served via /ui-icon/ whitelist.
- fetch_dota2_logo.py fetches the transparent emblem asset.
- Docs: CHANGELOG / README / DESIGN / AGENTS updated.
voson
1d0428b4a3