Add README to nodejs/azure-ai-streaming and fix broken links

[rido-min]

This pull request primarily introduces a new sample agent, azure-ai-streaming, and improves the documentation and usability of several Node.js sample agents. The most significant changes include the addition of the streaming agent sample, updates to documentation for clarity and accuracy, and enhancements to the agent code for better user experience. Below are the most important changes grouped by theme:

Add README to azure-ai-streaming for node

• Added a new azure-ai-streaming agent sample, including a comprehensive README.md that explains prerequisites, setup, running instructions, and integration with the Microsoft 365 Agents Playground and Azure Bot Service.

Documentation Improvements

• Updated references in multiple README files (auto-signin, copilotstudio-skill, obo-authorization) to point to the correct Microsoft documentation for Azure Bot authentication setup. [1] [2] [3] [4]
• Improved descriptions and instructions in the cards and langchain-multiturn sample READMEs for clarity, consistency, and to reflect use of the Express framework and the Agents Playground tool. [1] [2]R1, [3] [4]

Usability Enhancements

• Added a new test-tool script to azure-ai-streaming/package.json for launching the Agents Playground, improving the developer experience.
• Updated the welcome message in azure-ai-streaming/src/agent.ts for clarity and added feedback handling for invoke activities.

Miscellaneous

• Updated the name field in azure-ai-streaming/package-lock.json to match the new sample.