feat: add say hello and exit tool

[murrayju]

Summary

• Added a new sayHello tool that returns a greeting message and then gracefully exits the server
• Demonstrates basic server initialization and shutdown functionality for the MCP server

Test plan

• The tool accepts no input parameters
• Returns a greeting message: "Hello from Tiger Memory MCP Server!"
• Server exits cleanly after responding (with a 100ms delay to ensure the response is sent)
• Build passes with no TypeScript errors

🤖 Generated with Claude Code

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

---

Hermes Agent seems not to be a GitHub user. You need a GitHub account to be able to sign the CLA. If you have already a GitHub account, please add the email address used for this commit to your account.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}