chore: release v1.0.7

Playout: slate fallback, strict ffprobe validation, Prometheus metrics
Chat: history on join, DM offline delivery, env-config rate limits,
  Redis auto-reconnect, heartbeat, ban/mute enforcement, DM metrics
Viewer: presence indicators, schedule overlay, public /api/schedule
Admin: playlist drag-reorder, schedule overrides CRUD, user actions,
  inline mod buttons, CSV export, config editor, restart buttons,
  upload normalization gate, analytics time range
nginx: CORS preflight, JSON health, stub_status
Docs: test-lab vs production distinction across all configs/docs
Infra: Redis maxmemory, CD health IP-agnostic, slate volume mount

backend/playout/Dockerfile

@@ -18,8 +18,8 @@ RUN apk add --no-cache \
     bash
 # Set working directory for playout
 WORKDIR /app
-# Create directories for playlist, media, and HLS output
-RUN mkdir -p /app/hls /app/media /app/playlists
+# Create directories for playlist, media, HLS output, and emergency slate
+RUN mkdir -p /app/hls /app/media /app/playlists /app/slate
 # Copy the playout start script and the built playlist manager binary
 COPY start-playout.sh /app/
 # Copy demo data for out-of-the-box playout