feat: Update Docker and Kubernetes for database infrastructure

- Update backend Dockerfile with PostgreSQL deps and entrypoint
- Add entrypoint.sh with db/redis wait and auto-migration
- Add /ready endpoint for Kubernetes readiness probe
- Enhance /health endpoint with database and Redis status
- Update k8s deployment with PostgreSQL and Redis services
- Add proper secrets management for database credentials
- Update k8s readiness probe to use /ready endpoint

docker/backend/entrypoint.sh

@@ -0,0 +1,66 @@
+#!/bin/bash
+set -e
+
+echo "🚀 Starting Document Translation API..."
+
+# Wait for database to be ready (if DATABASE_URL is set)
+if [ -n "$DATABASE_URL" ]; then
+    echo "⏳ Waiting for database to be ready..."
+    
+    # Extract host and port from DATABASE_URL
+    # postgresql://user:pass@host:port/db
+    DB_HOST=$(echo $DATABASE_URL | sed -e 's/.*@\([^:]*\):.*/\1/')
+    DB_PORT=$(echo $DATABASE_URL | sed -e 's/.*:\([0-9]*\)\/.*/\1/')
+    
+    # Wait up to 30 seconds for database
+    for i in {1..30}; do
+        if python -c "
+import socket
+s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+try:
+    s.connect(('$DB_HOST', $DB_PORT))
+    s.close()
+    exit(0)
+except:
+    exit(1)
+" 2>/dev/null; then
+            echo "✅ Database is ready!"
+            break
+        fi
+        echo "   Waiting for database... ($i/30)"
+        sleep 1
+    done
+    
+    # Run database migrations
+    echo "📦 Running database migrations..."
+    alembic upgrade head || echo "⚠️  Migration skipped (may already be up to date)"
+fi
+
+# Wait for Redis if configured
+if [ -n "$REDIS_URL" ]; then
+    echo "⏳ Waiting for Redis..."
+    REDIS_HOST=$(echo $REDIS_URL | sed -e 's/redis:\/\/\([^:]*\):.*/\1/')
+    REDIS_PORT=$(echo $REDIS_URL | sed -e 's/.*:\([0-9]*\)\/.*/\1/')
+    
+    for i in {1..10}; do
+        if python -c "
+import socket
+s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+try:
+    s.connect(('$REDIS_HOST', $REDIS_PORT))
+    s.close()
+    exit(0)
+except:
+    exit(1)
+" 2>/dev/null; then
+            echo "✅ Redis is ready!"
+            break
+        fi
+        echo "   Waiting for Redis... ($i/10)"
+        sleep 1
+    done
+fi
+
+# Start the application
+echo "🎯 Starting uvicorn..."
+exec uvicorn main:app --host 0.0.0.0 --port ${PORT:-8000} --workers ${WORKERS:-4}