Add optional oh-my-opencode-slim multi-agent orchestration support

Integrate oh-my-opencode-slim as an opt-in feature via INSTALL_OMOS build arg.
A single build arg installs Bun, tmux, and the plugin; runtime activation is
controlled by ENABLE_OMOS and related env vars in the entrypoint.

entrypoint-user.sh

@@ -68,5 +68,54 @@ EOF
   esac
 fi
 
+# ── oh-my-opencode-slim setup (multi-agent orchestration) ────────────
+# Activated by ENABLE_OMOS=true. Requires the image to be built with
+# INSTALL_OMOS=true (which installs bun + the oh-my-opencode-slim package).
+OMOS_CONFIG="$CONFIG_DIR/oh-my-opencode-slim.json"
+
+if [ "${ENABLE_OMOS:-false}" = "true" ]; then
+  if ! command -v bunx &>/dev/null; then
+    echo "WARNING: ENABLE_OMOS=true but bun is not installed."
+    echo "Rebuild with: docker compose build --build-arg INSTALL_OMOS=true"
+  elif [ ! -f "$OMOS_CONFIG" ]; then
+    echo "Setting up oh-my-opencode-slim agents..."
+
+    # Determine installer flags
+    OMOS_TMUX_FLAG="no"
+    if [ "${OMOS_TMUX:-false}" = "true" ]; then
+      OMOS_TMUX_FLAG="yes"
+    fi
+
+    OMOS_SKILLS_FLAG="yes"
+    if [ "${OMOS_SKILLS:-true}" = "false" ]; then
+      OMOS_SKILLS_FLAG="no"
+    fi
+
+    bunx oh-my-opencode-slim@latest install \
+      --no-tui \
+      --tmux="${OMOS_TMUX_FLAG}" \
+      --skills="${OMOS_SKILLS_FLAG}"
+
+    echo "oh-my-opencode-slim configured successfully."
+  else
+    echo "oh-my-opencode-slim config found at $OMOS_CONFIG (use OMOS_RESET=true to overwrite)."
+
+    # Allow reset via env var (creates backup automatically)
+    if [ "${OMOS_RESET:-false}" = "true" ]; then
+      echo "OMOS_RESET=true — regenerating oh-my-opencode-slim config..."
+      OMOS_TMUX_FLAG="no"
+      [ "${OMOS_TMUX:-false}" = "true" ] && OMOS_TMUX_FLAG="yes"
+      OMOS_SKILLS_FLAG="yes"
+      [ "${OMOS_SKILLS:-true}" = "false" ] && OMOS_SKILLS_FLAG="no"
+
+      bunx oh-my-opencode-slim@latest install \
+        --no-tui \
+        --tmux="${OMOS_TMUX_FLAG}" \
+        --skills="${OMOS_SKILLS_FLAG}" \
+        --reset
+    fi
+  fi
+fi
+
 # ── Execute command ──────────────────────────────────────────────────
 exec "$@"