feat: podsteadr-player — minimal browse/pay/play client for podsteadr feeds

A separate, lightweight companion app: add any podsteadr server's URL,
browse its catalog and feeds, play free episodes directly, and buy
priced ones (NIP-07 signing, Lightning invoice + QR, then playback via
the paywall-gated download-url endpoint). No backend of its own — pure
static SPA, fetches other podsteadr instances directly.

Dark glassmorphism theme matching Archipelago's own dashboard (dark
background, translucent blurred panels, orange accent).

Vite's base path is configurable via VITE_BASE (build arg / .env, not
hardcoded) so the same image can be deployed either at a dedicated
port's root (no reverse-proxy prefix) or under a subpath behind a
shared HTTPS domain, depending on the host.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docker-compose.yml

@@ -0,0 +1,12 @@
+name: podsteadr-player
+
+services:
+  podsteadr-player:
+    build:
+      context: .
+      args:
+        VITE_BASE: ${VITE_BASE}
+    container_name: podsteadr-player
+    restart: unless-stopped
+    ports:
+      - "8097:8097"