[EnvConfigurator] Do not escape literal values in env files

[DjLeChuck]

Closes #1096

Problem

When a recipe defines a value wrapped in single quotes - for example to store a JSON array:

{
  "dotenv": {
    "dev": {
      "ALLOWED_LANGUAGES": "'[\"en\",\"de\",\"es\"]'"
    }
  }
}

The configurator incorrectly wrapped the value in double quotes and escaped the inner double quotes, producing:

ALLOWED_LANGUAGES="'[\"en\",\"de\",\"es\"]'"

Instead of the expected single-quoted dotenv literal:

ALLOWED_LANGUAGES='["en","de","es"]'

The dotenv format treats single-quoted values as fully literal strings (no escape processing), which makes them the natural fit for JSON content.

Solution

Skip the double-quote wrapping when the value already starts and ends with a single quote. Any other value continues through the existing escaping path introduced in #200.

// Before
if (false !== strpbrk($value, " \t\n&!\"")) {
  $value = '"'.str_replace([...], [...], $value).'"';
}

// After
if (!str_starts_with($value, "'") && !str_ends_with($value, "'") && false !== strpbrk($value, "\t\n&!\"")) {
  $value = '"'.str_replace([...], [...], $value).'"';
}

Tests

Added a ALLOWED_LANGUAGES='["en","de","es"]' fixture to both EnvConfiguratorTest and
DotenvConfiguratorTest to cover this case, alongside the existing assertions for values that require double-quote escaping.

[DjLeChuck]

Should I fix Fabbot issues about code style?