refactor(random)!: configure the renderer by base URL as RENDERER_URL

The bot now takes the renderer's base URL and appends each /api/<name>
route itself, instead of taking the full /api/gif endpoint and swapping
its last path segment for /gacha and /genshin. The client, its files, and
its errors are named after the renderer rather than wheelofnames; the
/wheelofnames command keeps its name.

BREAKING CHANGE: WHEELOFNAMES_API_URL is replaced by RENDERER_URL, which
holds the base URL (e.g. http://renderer:3000) rather than the /api/gif
endpoint. compose.yml sets it, so Coolify needs no value.

.env.example

@@ -38,11 +38,11 @@ STICKER_PACK_NAME=miti99_by_miti99bot
 # Without it every /lol* fetch fails; the stale cache covers ≤60 min.
 LOL_PANDASCORE_TOKEN=
 
-# Optional /wheelofnames GIF and /gacha MP4 renderer: the renderer/ service in
-# this repository. compose.yml fixes this to http://renderer:3000/api/gif, so
-# set it only when running the bot outside compose. /gacha calls /api/gacha on
-# the same service. Leave blank to fall back to text selection.
-WHEELOFNAMES_API_URL=
+# Optional base URL of the animation renderer (the renderer/ service in this
+# repository) for /wheelofnames, /gacha and /genshin, e.g.
+# http://localhost:3000. compose.yml fixes it to http://renderer:3000, so set it
+# only when running the bot outside compose. Leave blank to fall back to text.
+RENDERER_URL=
 
 # ====================== Leave UNSET on self-host ==================
 # Defaults are correct for self-host: