feat(i18n): consume central translations from @escalated-dev/locale

[mpge]

Summary

Wires escalated-adonis to consume translations from the new central npm package @escalated-dev/locale. The package's translation loader now layers three sources, with later layers winning on key conflict:

1. Central package — @escalated-dev/locale/locales/{locale}/ (canonical, shared across every host plugin)
2. Bundled local — resources/lang/{locale}/messages.json (this package's existing files, kept as overrides)
3. Host overrides — resources/lang/overrides/{locale}/messages.json (new per-host override slot)

No translation content was modified. Existing call sites (t('tickets.created') etc.) keep working because the loader hoists messages.json keys to the top level for backwards compatibility.

Wiring

• package.json — added "@escalated-dev/locale": "^0.1.0" to dependencies.
• src/support/i18n.ts — replaced the single-source loader with a layered loader that resolves the central package via createRequire, deep-merges the bundled local files on top, and finally deep-merges any host-supplied overrides under resources/lang/overrides/.
• stubs/config/i18n.stub — new stub that ships a canonical config/i18n.ts for host apps using @adonisjs/i18n v3+ directly. Chains two loaders.fs(...) entries (central path resolved via require.resolve('@escalated-dev/locale/package.json'), then app.languageFilesPath()) in order so local resources override the central package.
• resources/lang/overrides/.gitkeep + README.md — new directory with documentation of the layering pattern and a sample @adonisjs/i18n config snippet.
• README.md / CHANGELOG.md — documented the new i18n source-of-truth.

Blocked on escalated-dev/escalated-locale v0.1.0 publish

CI will fail on npm install until @escalated-dev/locale@0.1.0 is published to npm. Mark merge-ready once the upstream package ships. Expected error:

npm error code E404
npm error 404 Not Found - GET https://registry.npmjs.org/@escalated-dev%2flocale - Not found
npm error 404 '@escalated-dev/locale@^0.1.0' is not in this registry.

The runtime loader already handles the missing-package case gracefully (resolveCentralLangDir() returns null and the bundled local files are used alone), so local development without the published package keeps working.

Test plan

• npm install succeeds once @escalated-dev/locale@0.1.0 is published
• npm run build (or tsc) passes
• node --test tests/*.test.js continues to pass — no translation regressions
• Manual: add a key only to the central package, verify t('newKey') resolves
• Manual: add the same key to resources/lang/en/messages.json, verify the local value wins
• Manual: add the same key to resources/lang/overrides/en/messages.json, verify the override wins