feat(deploy): add brain/app roles for GPU-split deployment

Run the GPU-heavy compute (Whisper STT, Ollama LLM, TTS) on a dedicated
brain host and the bot + browser on a separate no-GPU app host, talking
over the LAN.

- supervisord: new `brain` role (bridge only) and `app` role (bot +
  desktop/Chrome, no local bridge); `full`/`browser`/`bot` unchanged.
- compose: make BRIDGE_URL overridable (was hardcoded to loopback, which
  prevented the bot from reaching a remote bridge).
- docs: DEPLOY.md "GPU split" layout with per-host .env blocks; document
  the new roles in run-if-role.sh and .env.example.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

docker-compose.yml

@@ -106,10 +106,17 @@ services:
       # on short/noisy Discord speech. Lower to 1 for minimum latency.
       STT_BEAM_SIZE: ${STT_BEAM_SIZE:-5}
       VOICE_SILENCE_MS: ${VOICE_SILENCE_MS:-600}
-      BRIDGE_URL: http://127.0.0.1:8765
-      # Split-deployment role: full (default, all-in-one), browser (only the
-      # desktop + Chrome + CDP, reused over the LAN), or bot (only bot + bridge
-      # + TTS, driving a remote browser via CDP_HOST). See docker/run-if-role.sh.
+      # Where the bot reaches the brain bridge (STT + reply + TTS). Loopback for
+      # all-in-one. In a GPU-split layout the bot host (JARVIS_ROLE=app) points
+      # this at the brain host: BRIDGE_URL=http://192.168.10.9:8765 (that host
+      # runs JARVIS_ROLE=brain with BRIDGE_HOST=0.0.0.0 + SETTINGS_PUBLISH_BIND=0.0.0.0).
+      BRIDGE_URL: ${BRIDGE_URL:-http://127.0.0.1:8765}
+      # Split-deployment role (see docker/run-if-role.sh):
+      #   full    (default) everything in one container
+      #   browser only desktop + Chrome + control-server (driven over the LAN)
+      #   bot     only bot + bridge + TTS (drives a remote browser)
+      #   brain   only the bridge (STT + reply + TTS) — GPU host, no bot/desktop
+      #   app     bot + browser/desktop, NO local bridge (uses a remote brain)
       JARVIS_ROLE: ${JARVIS_ROLE:-full}
       # Chrome CDP bind address INSIDE the container. 0.0.0.0 lets a remote bot
       # (JARVIS_ROLE=bot on another PC) drive this host's browser. Loopback by