feat: enhance AI tool support and clarify documentation (v2.5.1)

- Update tool descriptions to clarify ANY node can be used as AI tool
- Add get_node_as_tool_info to available tools in README
- Enhance workflow validation tool descriptions for AI connections
- Update README with v2.5.1 release notes
- Remove redundant _General__Scrape_with_HTTP_tool.json file
- Bump version to 2.5.1 in package.json

The key insight: ANY n8n node can be connected to an AI Agent's tool
port, not just those marked with usableAsTool=true. This update makes
that clear throughout the documentation and tool descriptions.

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

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "n8n-mcp",
-  "version": "2.4.2",
+  "version": "2.5.1",
   "description": "Integration between n8n workflow automation and Model Context Protocol (MCP)",
   "main": "dist/index.js",
   "scripts": {