feat: support for multiple registries

[xhyrom]

Fixes #107
Closes #129
Closes #122

Thanks for initial pull request #39 by @vitoorgomes
Thanks for #117 by @h3rmanj

[Copilot]

Pull Request Overview

This PR adds support for configuring multiple package registries (including scoped registries and authentication) in the setup-bun GitHub Action.
Key changes:

• Introduce a new registries input, parse it in src/registry.ts, and wire it through src/index.ts and src/action.ts.
• Replace manual TOML concatenation with parsing and stringifying via @iarna/toml in src/bunfig.ts, and update tests accordingly.
• Update documentation (README.md, action.yml) and CI pipeline to cover the new feature.

Reviewed Changes

Copilot reviewed 12 out of 15 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/tsconfig.json	Add test-specific TS config for Bun types
tests/registry.spec.ts	New unit tests for parseRegistries covering various input formats
tests/bunfig.spec.ts	New unit tests for writeBunfig, merging and formatting bunfig.toml
src/registry.ts	Implement parseRegistries to parse multi‐registry input
src/index.ts	Wire in registries input and maintain backwards compatibility
src/bunfig.ts	Switch to TOML parse/stringify for bunfig.toml generation
src/action.ts	Pass the new registries array into writeBunfig
package.json	Add @iarna/toml and Bun type definitions
bunfig.toml	Remove the placeholder bunfig template
action.yml	Define the new registries input and deprecate registry-url/scope
README.md	Document the registries input and format options
.github/workflows/test.yml	Add a CI job for running tests and example custom-registry test

Comments suppressed due to low confidence (4)

action.yml:20

• The registries input should explicitly specify type: string for clearer action metadata and validation.

  registries:

src/bunfig.ts:3

• The default stringify(config) may not produce the nested table indentation or ordering expected by your tests. Consider using stringify(config, null, 2) or building the TOML sections manually to preserve two-space indentation and the precise ordering.

import { parse, stringify } from "@iarna/toml";

src/bunfig.ts:1

• The Registry type is imported but not re-exported here, yet src/action.ts tries to import it from this module. Add export type { Registry } from './registry'; to re-export it or adjust the import in action.ts to pull directly from registry.ts.

import { existsSync, readFileSync, writeFileSync } from "node:fs";

src/action.ts:15

• There is no Registry export in bunfig.ts, so this import will fail. Either import Registry from ./registry here or re-export it from bunfig.ts.

import { writeBunfig, Registry } from "./bunfig";