fix: implement MCP Streamable HTTP protocol for Cursor integration

- Replace basic JSON-RPC implementation with Streamable HTTP protocol
- Add support for GET (SSE) and POST (JSON-RPC) requests
- Update protocol version from 2024-11-05 to 2025-03-26
- Fix list_feeds tool definition to match actual API (remove unused page/pageSize params)
- Add ping method support for MCP Inspector
- Update Cursor configuration to use url field instead of curl command
- Add comprehensive MCP integration documentation

Fixes #32

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

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

.cursor/mcp.json

@@ -0,0 +1,8 @@
+{
+    "mcpServers": {
+        "xiaohongshu-mcp": {
+            "url": "http://localhost:18060/mcp",
+            "description": "小红书内容发布服务 - MCP Streamable HTTP"
+        }
+    }
+}