Adds an opt-in `?format=ios` query parameter to
`GET /api/gamification/achievements`. When set, the response collapses
the existing `{ achievements, summary }` envelope into a flat
`Achievement[]` with translated `title`/`description` (server-side `t()`
honouring `Accept-Language` + `user.locale`) and `progress` normalised
to 0..1.
Default response (no query param) is unchanged. Existing web client
keeps receiving the wrapped `{ achievements, summary }` plus i18n keys
exactly as before.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
