multistreaming: scenes/composition, installer build support, service updates

- multistreaming (new): RTMP ingest + multi-platform fan-out with pluggable providers (Twitch/YouTube/Kick/custom), zero-knowledge key vaults, Authelia OIDC auth, shared rooms with editor/streamer roles, single-use invites, per-account streaming grants, and scenes & composition (grid/PiP layouts, text/image overlays, per-output audio routing).
- installer: support Dockerfile build in metadata (not just image) and RSA key generation for the Authelia OIDC JWKS.
- authelia: add OIDC provider with portainer + multistreaming clients (public + PKCE).
- services: remove allprox; add nginx-proxy-manager and portainer; update lldap; regenerate catalog.

services/multistreaming/Dockerfile

@@ -0,0 +1,45 @@
+# multistreaming — ingest one RTMP feed and restream it to many targets.
+# Build: docker build -t multistreaming .
+# Run:   docker run -p 1935:1935 -p 8080:8080 -v ms_data:/data multistreaming
+
+# ---- frontend build stage ------------------------------------------------
+FROM node:22-alpine AS web
+WORKDIR /web
+COPY web/package.json web/package-lock.json ./
+RUN npm ci
+COPY web/ ./
+RUN npm run build
+
+# ---- backend deps stage --------------------------------------------------
+FROM node:22-alpine AS deps
+WORKDIR /app
+COPY package*.json ./
+RUN npm ci --omit=dev
+
+# ---- runtime stage --------------------------------------------------------
+FROM node:22-alpine
+WORKDIR /app
+
+# FFmpeg does the actual fan-out (remux passthrough, or re-encode for scenes).
+# font-dejavu is a hard runtime dependency of the drawtext text overlay filter.
+RUN apk add --no-cache ffmpeg font-dejavu
+
+ENV NODE_ENV=production
+
+COPY --from=deps /app/node_modules ./node_modules
+COPY src ./src
+COPY --from=web /web/dist ./web/dist
+
+# Persistent state (vaults, rooms, accounts, feeds) lives here; mount a volume.
+# Pre-create it and hand ownership to the runtime user so a fresh named
+# volume is writable without root.
+RUN mkdir -p /data && chown node:node /data
+VOLUME ["/data"]
+ENV DATA_DIR=/data \
+    RTMP_PORT=1935 \
+    HTTP_PORT=8080
+
+EXPOSE 1935 8080
+
+USER node
+CMD ["node", "src/index.js"]