feat: Add completion and resource template support

[gavinaboulhosn]

• Add support for MCP completions
• Implement URI templates for dynamic resources
• Add completion handlers for prompts and resources
• Update documentation with new features and examples

This implementation follows the MCP specification for completions and resource templates

References:
https://spec.modelcontextprotocol.io/specification/server/resources/#resource-templates
https://spec.modelcontextprotocol.io/specification/server/utilities/completion/

[gavinaboulhosn]

Following the initial implementation, I'm adding these type safety improvements

• better type inference for completion arguments:

  async complete?<K extends keyof TArgs>(
    argumentName: K,
    value: z.infer<TArgs[K]["type"]>
  ): Promise<PromptCompletion>;

  This ensures that completion values match their argument's schema type.

For example, with this improvement:

interface GreetingInput {
  language: z.ZodString;
  count: z.ZodNumber;
}

TypeScript will properly type value based on the argument - string for "language", number for "count".

[QuantGeekDev]

This looks sweet, thanks for your contribution @gavinaboulhosn - I'll try to review this over the following 24 hours
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[gavinaboulhosn]

I'm going to tests this a little more. There isn't support for completions in tools like MCP inspector so I'm working on potentially opening a PR there to help me verify these changes.

[QuantGeekDev]

I'm going to tests this a little more. There isn't support for completions in tools like MCP inspector so I'm working on potentially opening a PR there to help me verify these changes.

Got it - sorry I haven't been able to get to this yet. How can I verify that this works? What's your email / discord? I'd love to connect and chat thru these changes and see how I can help. Would love to add more features to mcp inspector too