Create upgrade-agent workflow for library maintenance

Added a workflow for automated library upgrades in Node.js.

Author: rahu619

.github/workflows/upgrade-agent.md

@@ -0,0 +1,19 @@
+---
+name: Library Maintainer Agent
+trigger:
+  issue_comment:
+    contains: "@github-agent upgrade"
+permissions:
+  contents: write
+  pull-requests: write
+  issues: write
+---
+
+# Task: Dependency & Environment Upgrade
+You are a Senior Node.js Engineer. When triggered:
+1. Identify the latest LTS version of Node.js and the latest stable TypeScript.
+2. Update `package.json` and `package-lock.json`.
+3. Run `npm install` and `npm test`.
+4. If tests fail, analyze the error, fix the source code in `src/`, and retry.
+5. Once successful, open a Pull Request titled "chore: automated library upgrade".
+6. Summarize the changes and any breaking fixes you had to apply.