feat: SSE (Server-Sent Events) support for n8n integration

- Added SSE server implementation for real-time event streaming
- Created n8n compatibility mode with strict schema validation
- Implemented session management for concurrent connections
- Added comprehensive SSE documentation and examples
- Enhanced MCP tools with async execution support
- Added Docker Compose configuration for SSE deployment
- Included test scripts and integration tests

🤖 Generated with [Claude Code](https://claude.ai/code)

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

scripts/test-sse.sh

@@ -0,0 +1,104 @@
+#!/bin/bash
+
+# Test script for SSE server
+# Usage: ./scripts/test-sse.sh
+
+SERVER_URL="${SERVER_URL:-http://localhost:3000}"
+AUTH_TOKEN="${AUTH_TOKEN:-test-secure-token-123456789}"
+
+echo "🧪 Testing SSE Server Implementation"
+echo "Server URL: $SERVER_URL"
+echo "Auth Token: ${AUTH_TOKEN:0:8}..."
+echo ""
+
+# Function to test endpoint
+test_endpoint() {
+    local method=$1
+    local endpoint=$2
+    local data=$3
+    local headers=$4
+    
+    echo -n "Testing $method $endpoint... "
+    
+    if [ "$method" = "GET" ]; then
+        response=$(curl -s -w "\n%{http_code}" -X GET "$SERVER_URL$endpoint" $headers)
+    else
+        response=$(curl -s -w "\n%{http_code}" -X POST "$SERVER_URL$endpoint" \
+            -H "Content-Type: application/json" \
+            $headers \
+            -d "$data")
+    fi
+    
+    http_code=$(echo "$response" | tail -n1)
+    body=$(echo "$response" | head -n-1)
+    
+    if [ "$http_code" = "200" ]; then
+        echo "✅ OK ($http_code)"
+        if [ -n "$body" ]; then
+            echo "  Response: $(echo "$body" | jq -c . 2>/dev/null || echo "$body")"
+        fi
+    else
+        echo "❌ FAILED ($http_code)"
+        if [ -n "$body" ]; then
+            echo "  Error: $body"
+        fi
+    fi
+    echo ""
+}
+
+# Test health check
+test_endpoint "GET" "/health" "" ""
+
+# Test SSE connection (limited test with curl)
+echo -n "Testing SSE connection... "
+timeout 2 curl -s -N -H "Authorization: Bearer $AUTH_TOKEN" "$SERVER_URL/sse" > /tmp/sse-test.log 2>&1 &
+SSE_PID=$!
+sleep 1
+
+if kill -0 $SSE_PID 2>/dev/null; then
+    echo "✅ Connection established"
+    kill $SSE_PID 2>/dev/null
+    if [ -s /tmp/sse-test.log ]; then
+        echo "  Initial events:"
+        cat /tmp/sse-test.log | head -5
+    fi
+else
+    echo "❌ Connection failed"
+fi
+echo ""
+
+# Test legacy MCP endpoint
+test_endpoint "POST" "/mcp" '{"jsonrpc":"2.0","method":"tools/list","id":1}' "-H 'Authorization: Bearer $AUTH_TOKEN'"
+
+# Test invalid auth
+echo -n "Testing authentication rejection... "
+response=$(curl -s -w "\n%{http_code}" -X GET "$SERVER_URL/sse" -H "Authorization: Bearer invalid-token")
+http_code=$(echo "$response" | tail -n1)
+if [ "$http_code" = "401" ]; then
+    echo "✅ Correctly rejected ($http_code)"
+else
+    echo "❌ Expected 401, got $http_code"
+fi
+
+# Summary
+echo ""
+echo "📊 Test Summary:"
+echo "SSE server endpoint: $SERVER_URL/sse"
+echo "Message endpoint: $SERVER_URL/mcp/message"
+echo "Legacy endpoint: $SERVER_URL/mcp"
+
+# Instructions for manual testing
+echo ""
+echo "📝 Manual Testing Instructions:"
+echo ""
+echo "1. Connect to SSE stream:"
+echo "   curl -N -H \"Authorization: Bearer $AUTH_TOKEN\" $SERVER_URL/sse"
+echo ""
+echo "2. In another terminal, get the client ID from the connected event and send a message:"
+echo "   curl -X POST $SERVER_URL/mcp/message \\"
+echo "     -H \"Authorization: Bearer $AUTH_TOKEN\" \\"
+echo "     -H \"X-Client-ID: <client-id-from-sse>\" \\"
+echo "     -H \"Content-Type: application/json\" \\"
+echo "     -d '{\"jsonrpc\":\"2.0\",\"method\":\"tools/list\",\"id\":1}'"
+echo ""
+echo "3. You should see the response in the SSE stream"