fix: Add support for external PostgreSQL and Redis instances

Implements smart detection that allows users to provide external DATABASE_URL
or REDIS_URL. When external services are detected, internal instances are
automatically disabled to save resources. Maintains full backward compatibility
with existing setup

docker/unified/postgres-start.sh

@@ -0,0 +1,39 @@
+#!/bin/bash
+# PostgreSQL startup wrapper for unified container
+# Smart supervisor: detects external PostgreSQL and sleeps instead of starting local instance
+#
+# Behavior:
+# - If DATABASE_URL points to external host (not 127.0.0.1/localhost), sleep infinity
+# - Otherwise, start local PostgreSQL instance
+
+set -e
+
+# Load environment from /etc/environment (set by entrypoint)
+if [ -f /etc/environment ]; then
+    set -a
+    source /etc/environment
+    set +a
+fi
+
+echo "[PostgreSQL] Checking for external database configuration..."
+
+# Extract host from DATABASE_URL
+# Format: postgresql://user:pass@host:port/db
+if [ -n "$DATABASE_URL" ]; then
+    # Extract the host part (between @ and :port or /)
+    DB_HOST=$(echo "$DATABASE_URL" | sed -n 's|.*@\([^:/]*\).*|\1|p')
+    
+    echo "[PostgreSQL] Detected DATABASE_URL host: $DB_HOST"
+    
+    # Check if host is external (not localhost or 127.0.0.1)
+    if [ "$DB_HOST" != "127.0.0.1" ] && [ "$DB_HOST" != "localhost" ]; then
+        echo "[PostgreSQL] ✅ External PostgreSQL detected at $DB_HOST"
+        echo "[PostgreSQL] Skipping local PostgreSQL startup - sleeping to keep supervisord happy"
+        exec sleep infinity
+    fi
+fi
+
+echo "[PostgreSQL] Starting local PostgreSQL server..."
+
+# Start PostgreSQL as postgres user
+exec /usr/lib/postgresql/16/bin/postgres -D /var/lib/postgresql/data