feat: TypeScript memory client

[0xpolarzero]

Warning

This PR is part of a stacked PR chain. Review/merge in order:
#144
#145
#143
> #147

Overview

Adds an in-memory TypeScript client that calls incur commands directly from a Cli instance without running an HTTP server.

API

import { create, createMemoryClient } from 'incur'
import { z } from 'zod'

const cli = create('project')
  .command('deploy', {
    args: z.object({ id: z.string() }),
    options: z.object({ dryRun: z.boolean().default(false) }),
    output: z.object({ id: z.string(), url: z.string() }),
    run: ({ args, options }) => ({
      id: args.id,
      url: options.dryRun ? 'preview://deploy' : 'https://example.com/deploy',
    }),
  })
  .command('logs', {
    args: z.object({ id: z.string() }),
    output: z.object({ line: z.string() }),
    async *run() {
      yield { line: 'deploy started' }
    },
  })

const client = createMemoryClient(cli)

const result = await client('project deploy')({
  args: { id: 'p1' },
  options: { dryRun: true },
})
//    ^? { id: string; url: string }

const stream = await client('project logs')({
  args: { id: 'p1' },
})
//    ^? AsyncIterable<{ line: string }>

Changes

• Add createMemoryClient(cli) with the same typed call shape as createClient.
• Share structured RPC execution between HTTP and in-memory clients.
• Preserve validation, middleware, errors, CTAs, root commands, and streaming cleanup across both paths.
• Extend Cli command maps with output metadata and structural stream metadata for local client inference.

Tests

• Adds memory client runtime coverage for data, validation, errors, middleware, root commands, streams, and cancellation.
• Adds type tests for createMemoryClient(cli) inference, mounted CLIs, outputs, and streaming calls.
• Adds RPC coverage for root command execution and stream cancellation.

[0xpolarzero]

Will reopen better PRs after playing around and figuring out the best API.