Add Learn MCP Server tool-calling sample

[pdebruin]

Adds JS and C# samples that use Foundry Local with the Learn MCP Server to create a doc-grounded Q&A assistant.

The model calls a search_docs tool that queries learn.microsoft.com via MCP (JSON-RPC over HTTP), then synthesizes answers from official Microsoft documentation. All inference runs locally on-device.

JS sample (samples/js/learn-mcp-tool-calling/):

• app.js, package.json
• Tested and working end-to-end

C# sample (samples/cs/learn-mcp-tool-calling/):

• Program.cs, LearnMcpToolCalling.csproj, LearnMcpToolCalling.sln
• Builds successfully, but runtime-blocked by Betalgo version mismatch (Migrate C# library and samples from Betalgo.Ranul.OpenAI to official OpenAI NuGet package #632) — same issue affects all existing C# tool-calling samples

README updates:

• samples/README.md — updated JS count (12 → 13) and C# count (12 → 13)
• samples/js/README.md — added table entry
• samples/cs/README.md — added table entry

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Pull request overview

Adds a new JavaScript sample demonstrating tool-calling with Foundry Local, grounded by Microsoft Learn documentation retrieved via the Learn MCP Server (JSON-RPC over HTTP).

Changes:

• Adds a new JS sample (samples/js/learn-mcp-tool-calling/) with an interactive CLI assistant that calls a search_docs tool backed by Learn MCP Server.
• Updates the JS samples index to include the new sample.
• Updates the top-level samples README to reflect the new JS sample count (13).

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
samples/js/learn-mcp-tool-calling/package.json	Adds a runnable Node.js sample package using foundry-local-sdk (+ WinML optional dep).
samples/js/learn-mcp-tool-calling/app.js	Implements the CLI assistant, MCP-backed search_docs tool, and a tool-calling loop.
samples/js/README.md	Adds the new sample to the JS samples table.
samples/README.md	Updates JavaScript sample count from 12 to 13 and mentions Learn MCP Server.

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[Copilot]

JSON.parse(toolCall.function.arguments) can throw (missing/empty/invalid JSON) and will crash the sample mid-conversation. Consider a safe parse with a default (e.g., {}) and on parse failure push a role:'tool' error result for that tool_call_id instead of throwing, so the loop can continue gracefully.

Suggested change

	const args = JSON.parse(toolCall.function.arguments);
	const rawArguments = typeof toolCall.function.arguments === 'string' && toolCall.function.arguments.trim() !== ''
	? toolCall.function.arguments
	: '{}';
	let args;
	try {
	args = JSON.parse(rawArguments);
	} catch (error) {
	messages.push({
	role: 'tool',
	tool_call_id: toolCall.id,
	content: JSON.stringify({
	error: `Invalid tool arguments for ${functionName}: ${error.message}`
	})
	});
	continue;
	}