fix: respect NO_COLOR environment variable in dev format

[armorbreak001]

Problem

The dev format always outputs ANSI-colored text, ignoring the widely-adopted NO_COLOR environment variable (https://no-color.org/).

This causes accessibility issues for users with limited vision who may have difficulty reading colored terminal output.

Fix

When NO_COLOR is set (even to an empty string), the dev format outputs plain text without ANSI escape codes.

Changes

• Modified the dev format function in index.js to check process.env.NO_COLOR
• When set, compiles a plain-text format instead of a colored one
• Cache key includes a -nc suffix to separate plain-text and colored compiled formats

Testing

• All 88 existing tests pass
• Manual test:

  NO_COLOR=1 node -e "require('./index.js')('dev')" | cat -v | grep '\\x1b'
  # Should return nothing (no ANSI codes)

Fixes #302