feat: add configurable log levels via env.logLevel

[taronsung]

Summary

Adds configurable logging levels to control library verbosity, as requested in #117.

Changes

• Add LogLevel enum with NONE, ERROR, WARNING, INFO, DEBUG levels
• Add env.logLevel configuration (defaults to WARNING)
• Create logger utility that respects the configured log level
• Update console.log/warn calls in pipelines.js to use logger
• Export LogLevel and logger from main entry point

Usage

import { env, LogLevel, logger } from '@huggingface/transformers';

// Set log level to suppress all logs
env.logLevel = LogLevel.NONE;

// Set log level to show only errors
env.logLevel = LogLevel.ERROR;

// Set log level to show warnings and above (default)
env.logLevel = LogLevel.WARNING;

// Set log level to show info messages and above
env.logLevel = LogLevel.INFO;

// Set log level to show all messages including debug
env.logLevel = LogLevel.DEBUG;

// Use the logger directly
logger.info('Model loaded successfully');
logger.warn('Deprecated method used');
logger.error('Failed to load model');
logger.debug('Token count:', tokens.length);

Notes

• This PR focuses on the infrastructure and updates pipelines.js as a starting point
• Other files with console.warn/error calls can be migrated in follow-up PRs
• The TextStreamer output in streamers.js was intentionally not changed as it's user-facing streaming output, not logging

Closes #117

[xenova]

Hi @taronsung 👋 Thanks for the PR! I do like this feature, and it's definitely something I think we can implement. Since we're in the process of a relatively large refactor (v4: https://github.com/huggingface/transformers.js/tree/v4), could you update the base to be that branch? From the looks of it, it'd just entail moving the new files into the packages/transformers folder... all else should stay mostly similar.

We could also take inspiration from the python transformers library... maybe implementing methods like warning_once (for example) to only log once in case of repeated calls. WDYT? Edit: Actually, maybe not worth it because browser runtimes typically collapse duplicate logs anyway.

[nico-martin]

I added some commits to the PR. Most of it is just more console. that I wanted to replace with logger., but I also added a mapping between our own logLevels and the ONNX_ENV.logLevel.

[nico-martin]

Is there a reason you want to export the logger? In my opinion that should stay in the library and should not be user facing.

[HuggingFaceDocBuilderDev]

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