Let a show's own theme override the configured color scheme

SUB/WAVE lets a show set its own color theme, which overrides the
station's default while that show is on air -- the station's own web UI
already does this (controller/src/routes/public.ts resolves it
server-side: activeShow?.themeId || station default). That resolved
value rides on /api/state's theme.active field, not /api/now-playing,
so this adds a second fetch (_fetch_show_theme) rather than reading an
existing response field.

Theme ids there use hyphens ("classic-light"); this app's COLOR_SCHEMES
keys use underscores ("classic_light") -- otherwise the same 8 names,
confirmed against SUB/WAVE's own theme registry (press-run-plates.ts),
so swapping the separator is enough to look it up directly.

Falls back to the user's configured color_scheme on a fetch failure, a
non-200 response, or an id this app doesn't recognize -- verified a
real reachable server returns a clean 404 for an unsupported path
(not a hard connection error), so that fallback path is exercised by
real servers, not just a theoretical case.

Verified against the live test station (currently "classic-light"):
renders with its light cream background/dark text/red accent instead
of the hardcoded cyberpunk default, confirming the override actually
takes effect.

subwave_nowplaying.star

@@ -196,6 +196,14 @@ def main(config):
     if not now["online"]:
         return render.Root(child = _with_background(_message_screen([now["station"], "offline"], colors), colors))
 
+    # A show's own theme override (if any) wins over the user's configured
+    # color_scheme, mirroring what SUB/WAVE's own web UI does -- see
+    # _fetch_show_theme. Falls back to the configured scheme on a fetch
+    # failure or an id this app doesn't recognize, rather than erroring.
+    show_theme_id = _fetch_show_theme(station_url)
+    if show_theme_id != None and show_theme_id in COLOR_SCHEMES:
+        colors = COLOR_SCHEMES[show_theme_id]
+
     art = _fetch_cover(station_url, now["subsonic_id"])
     progress = _track_progress(now["subsonic_id"], now["duration"])
 
@@ -958,6 +966,28 @@ def _format_time_temp(clock, weather):
 
     return " · ".join(parts)
 
+def _fetch_show_theme(station_url):
+    # SUB/WAVE lets a show override the station's default color theme
+    # (controller/src/routes/public.ts resolves this server-side already:
+    # activeShow?.themeId || station default). That resolved value rides
+    # on /api/state's theme.active, not /api/now-playing -- a separate
+    # fetch, not a field on the response this app already pulls.
+    #
+    # Theme ids there use hyphens (e.g. "classic-light"), this app's
+    # COLOR_SCHEMES keys use underscores ("classic_light") -- same 8
+    # names otherwise (confirmed against SUB/WAVE's own theme registry),
+    # so swapping the separator is enough to look it up directly rather
+    # than needing an explicit id-mapping table.
+    rep = http.get(station_url + "/api/state", ttl_seconds = NOWPLAYING_TTL)
+    if rep.status_code != 200:
+        return None
+
+    theme_id = (rep.json().get("theme", {}) or {}).get("active", "")
+    if not theme_id:
+        return None
+
+    return theme_id.replace("-", "_")
+
 def _fetch_cover(station_url, subsonic_id):
     if not subsonic_id:
         return None