feat(cli): support configuration via PINO_PRETTY_* environment variables

[mahmoodhamdi]

Summary

Closes #554.

Adds environment variable support to the pino-pretty CLI. All options are configurable with a PINO_PRETTY_ prefix and SCREAMING_SNAKE_CASE naming.

Priority: CLI flags > config file > env vars (env vars are lowest priority, acting as a global fallback).

Env var → CLI flag mapping

Environment Variable	CLI Flag
PINO_PRETTY_COLORIZE	--colorize
PINO_PRETTY_CRLF	--crlf
PINO_PRETTY_ERROR_PROPS	--errorProps
PINO_PRETTY_LEVEL_FIRST	--levelFirst
PINO_PRETTY_MINIMUM_LEVEL	--minimumLevel
PINO_PRETTY_CUSTOM_LEVELS	--customLevels
PINO_PRETTY_CUSTOM_COLORS	--customColors
PINO_PRETTY_USE_ONLY_CUSTOM_PROPS	--useOnlyCustomProps
PINO_PRETTY_ERROR_LIKE_OBJECT_KEYS	--errorLikeObjectKeys
PINO_PRETTY_MESSAGE_KEY	--messageKey
PINO_PRETTY_LEVEL_KEY	--levelKey
PINO_PRETTY_LEVEL_LABEL	--levelLabel
PINO_PRETTY_MESSAGE_FORMAT	--messageFormat
PINO_PRETTY_TIMESTAMP_KEY	--timestampKey
PINO_PRETTY_TRANSLATE_TIME	--translateTime
PINO_PRETTY_IGNORE	--ignore
PINO_PRETTY_INCLUDE	--include
PINO_PRETTY_HIDE_OBJECT	--hideObject
PINO_PRETTY_SINGLE_LINE	--singleLine

Boolean options accept true/1 and false/0 (case-insensitive). Invalid values are silently ignored.

Usage example

# Instead of:
myapp | pino-pretty --singleLine --levelFirst

# You can now use:
PINO_PRETTY_SINGLE_LINE=true PINO_PRETTY_LEVEL_FIRST=true myapp | pino-pretty

# Or in a .env / Docker environment:
PINO_PRETTY_IGNORE=pid,hostname
PINO_PRETTY_TRANSLATE_TIME=SYS:yyyy-mm-dd HH:MM:ss

Test plan

• 7 new tests in test/cli-env.test.js covering boolean options (true/1), string options, CLI-over-env priority, and invalid boolean value handling
• All 357 existing tests continue to pass (npm test)

[mcollina]

lgtm