feat: allow any valid ISO locale code in validation (#1583)

* feat: allow any valid ISO locale code in validation

Previously, locale code validation was restricted to a hardcoded list
of ~222 specific locales. This change updates the validation logic to
accept any valid locale code that conforms to ISO standards:

- ISO 639-1 language codes (2-letter)
- ISO 15924 script codes (4-letter, optional)
- ISO 3166-1 alpha-2 region codes (2-letter, optional)
- UN M.49 numeric region codes (3-digit, optional)

The validation now uses the comprehensive validation functions from
the @lingo.dev/_locales package, which includes 184 language codes,
200+ script codes, and 249 region codes.

Changes:
- Add @lingo.dev/_locales dependency to packages/spec
- Update localeCodeSchema to use isValidLocale() instead of hardcoded list
- Maintain backward compatibility with existing normalization
- All existing tests continue to pass

Benefits:
- Supports locale codes like en-NZ, de-LU, es-CO that weren't in the list
- Follows standard locale format validation
- Reduces maintenance burden of hardcoded locale lists

* docs: add changeset requirements to CLAUDE.md and create changeset

Author: maxprilutskiy

.changeset/allow-valid-locale-codes.md

@@ -0,0 +1,5 @@
+---
+"@lingo.dev/_spec": minor
+---
+
+Allow any valid ISO locale code in validation instead of hardcoded list. Validation now accepts any locale conforming to ISO 639-1, ISO 15924, ISO 3166-1, and UN M.49 standards.

CLAUDE.md

@@ -10,4 +10,10 @@
 
 ## Testing
 
-- When you add tests - make sure they pass
+- When you add tests - make sure they pass
+
+## Changesets
+
+- Every PR must include a changeset
+- Create changeset: `pnpm new` from repo root
+- For changes that don't need a release (e.g., README updates): `pnpm new:empty`

packages/spec/package.json

@@ -25,6 +25,7 @@
   "author": "",
   "license": "Apache-2.0",
   "dependencies": {
+    "@lingo.dev/_locales": "workspace:*",
     "zod": "^3.25.76",
     "zod-to-json-schema": "^3.24.5"
   },

packages/spec/src/locales.ts

@@ -1,4 +1,5 @@
 import Z from "zod";
+import { isValidLocale } from "@lingo.dev/_locales";
 
 const localeMap = {
   // Urdu (Pakistan)
@@ -246,7 +247,11 @@ export const localeCodes = [
 ] as LocaleCode[];
 
 export const localeCodeSchema = Z.string().refine(
-  (value) => localeCodes.includes(value as any),
+  (value) => {
+    // Normalize locale before validation
+    const normalized = normalizeLocale(value);
+    return isValidLocale(normalized);
+  },
   {
     message: "Invalid locale code",
   },