feat(@mastra/mcp): MCPConfiguration class

[TylerBarnes]

This PR:

1. Adds the new MCPConfiguration class from https://github.com/mastra-ai/mastra/blob/main/explorations/mcp-registry-client/README.md (minus the registry part)
2. tests for new class
3. updates docs, adds a code example (will add an example docs page next week). shows using tools vs toolsets and why/when you would use each
4. fixed a couple bugs in MastraMCPClient class
   • Passing server.env config would break commands like npx since PATH wasn't being passed in
   • There was no graceful shutdown when the process exited - so code saves would print massive errors from mcp servers when running mastra dev

Example:

const mcp = new MCPConfiguration({
  servers: {
    stockPrice: {
      command: 'npx',
      args: ['-y', 'tsx', './src/mastra/tools/stock-price.ts'],
      env: {
        FAKE_CREDS: 'let me in!',
      },
    },
    weather: {
      url: new URL('http://localhost:8080/sse'),
    },
  },
});

const toolsets = await mcp.getConnectedToolsets();
const tools = await mcp.getConnectedTools();

screenshot from running the cli code example (also works with mastra dev)

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🦋 Changeset detected

Latest commit: 5874164

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
mastra	Minor
@mastra/mcp	Minor
@mastra/dane	Patch

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