feat: add is_plural support for creating plural translation keys

[mattJurz]

Summary

• Add is_plural parameter to create_keys tool to support creating plural translation keys
• Accept translations as objects with CLDR plural categories (zero/one/two/few/many/other) instead of only plain strings
• Pass is_plural through the full stack: types → controller → service → Lokalise API

Motivation

Currently there is no way to create a plural key via the MCP tool. The Lokalise REST API supports is_plural: true on key creation (see Lokalise Node API docs), but the MCP tool doesn't expose this parameter. This means users must manually toggle "Set as plural key" in the Lokalise UI after creating keys via MCP.

Usage example

{
  "projectId": "123456.abcdef",
  "keys": [{
    "key_name": "items.count",
    "is_plural": true,
    "platforms": ["ios", "android", "web"],
    "translations": [
      {
        "language_iso": "en",
        "translation": {
          "one": "%s item",
          "other": "%s items"
        }
      },
      {
        "language_iso": "pl",
        "translation": {
          "one": "%s element",
          "few": "%s elementy",
          "many": "%s elementów",
          "other": "%s elementów"
        }
      }
    ]
  }]
}

Changes

File	Change
keys.types.ts	Added is_plural field + PluralFormsSchema + union type for translation
keys.service.ts	Pass is_plural to Lokalise API + updated CreateKeysParams interface
keys.controller.ts	Map is_plural from tool args to service params
keys.tool.ts	Updated tool description to document plural support

Test plan

• Create a non-plural key (existing behavior unchanged)
• Create a plural key with is_plural: true and object translations
• Verify plural key appears correctly in Lokalise UI with ONE/OTHER/FEW/MANY forms
• Verify non-plural keys still accept string translations

🤖 Generated with Claude Code