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>

Dockerfile

@@ -0,0 +1,18 @@
+# ---- build ----
+FROM docker.io/library/node:22-bookworm-slim AS build
+WORKDIR /build
+COPY package*.json ./
+RUN npm ci
+COPY . .
+# Root deploys (own port, no reverse-proxy prefix) leave this unset and default to '/'.
+ARG VITE_BASE=/
+ENV VITE_BASE=$VITE_BASE
+RUN npm run build
+
+# ---- runtime ----
+FROM docker.io/library/nginx:1.27-alpine
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+COPY --from=build /build/dist /usr/share/nginx/html
+EXPOSE 8097
+HEALTHCHECK --interval=30s --timeout=5s --retries=3 \
+    CMD wget -qO- http://localhost:8097/ >/dev/null || exit 1