fix(cli): fix ESM build and add --time flag

[dwego]

Summary

This PR fixes the CLI build environment for ESM (.mjs) output and adds the new --time flag to measure encode/decode execution time.

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Changes

• Fixed import path in bin/toon.mjs to use ../dist/index.mjs

• Updated dev entrypoint to run from cli-entry.ts

• Added new --time flag:

  toon --encode input.json --output output.toon --time

  Output example:

  ✔ Encoded `input.json` → `output.toon`
  ┌────────────────────────────┐
  │ Encode time: 0.153s        │
  └────────────────────────────┘
  

• Updated CLI documentation to include the --time option

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Why

Previous CLI builds failed in ESM mode due to .js import mismatch
The --time flag helps benchmark encoding/decoding performance
Improves overall developer experience and aligns with the TOON principles of token efficiency and simplicity

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Testing

npm run dev -- --encode input.json --output output.toon --time
toon --encode input.json --output output.toon --time
Verified outputs for both encode and decode modes

[johannschopplich]

Thanks a lot! Some thoughts:

• Actually, tsdown builds an index.js. That's why we have to import it.
• I like the idea of the time flag, but honestly, the encoding duration is negligible.

Appreciate your work, but I have do deny.