feat(rules): add scope-delimiter-style

[what1s1ove]

Description

This PR introduces a new rule, scope-delimiter-style, which validates that commit scopes use only the allowed delimiters. This ensures consistent behavior when custom delimiters are configured.

It also adds support for passing custom delimiters to the scope-enum and scope-case rules, allowing users to redefine how multi-segment scopes are split and validated.

The default delimiters (/, \, ,) remain unchanged unless explicitly overridden.

Documentation has been updated to reflect:

• support for object-based configuration in scope-enum and scope-case
• ability to customize delimiters
• introduction of the new scope-delimiter-style rule
• updated Multiple Scopes section describing configurable delimiters

This brings delimiter handling across all scope-related rules to a unified and configurable model.

Motivation and Context

Resolves #701

Current scope-related rules (scope-enum, scope-case) use hardcoded delimiters to split multi-segment scopes. This makes it impossible for users to adapt commitlint to projects that use different delimiter conventions.

This PR introduces configurable delimiters and a dedicated scope-delimiter-style rule, enabling consistent validation across all scope rules. It provides a unified and flexible way to define how scopes should be parsed and validated, solving the long-standing limitation described in the linked issue.

Usage examples

// commitlint.config.js

const delimiters = ["/"];

export default {
  rules: {
    "scope-delimiter-style": [2, "always", delimiters],
    "scope-enum": [2, "always", { scopeEnums: ["api", "core"], delimiters }],
    "scope-case": [2, "always", { cases: "kebab-case", delimiters }],
  };
};

echo "feat(api,cor): add new version" | commitlint 

# ⧗   input: feat(api,cor): add new version
# ✖   scope must be one of [api, core] [scope-enum]
# ✖   scope delimiters must be one of [/] [scope-delimiter-style]
# ✖   found 2 problems, 0 warnings

echo "feat(api/core): add new version" | commitlint

# success

How Has This Been Tested?

All changes are covered by an extended test suite:

• Updated existing tests for scope-enum and scope-case to ensure backward compatibility with default delimiters.

• Added new tests for object-based configuration, including custom delimiter lists and empty delimiter arrays.

• Added a full test suite for the new scope-delimiter-style rule, covering:

  • default behavior
  • custom delimiter configurations
  • always and never conditions
  • fallback to default delimiters
  • handling of special characters
  • non-delimiter characters such as - and _

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

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[escapedcat]

Pressed the copilot review. Have a look if any of that is valid or useful, thanks!

[what1s1ove]

Hey @escapedcat! Thanks a lot, some of Copilot's suggestions were pretty helpful. I've pushed the changes. Whenever you have a moment, could you take a look?

[escapedcat]

lgtm, @JounQin would you mind having a look?