Ship first non-English language pack for UI copy

[NickTheDevOpsGuy]

Summary

Once localization infrastructure exists, add the first translated language so the feature is real and testable.

Suggested target

Spanish is a strong first candidate because it has broad reach and is practical for early validation.

Scope

• Translate the highest-traffic UI strings.
• Verify modal layouts and button sizes with longer translated copy.
• Catch any hard-coded English strings still leaking into the UI.

Acceptance Criteria

• One complete non-English language is available from settings.
• Home, puzzle selection, play HUD, completion, and stats have translated copy.
• Mobile layout still fits translated strings without clipping.
• Missing translation keys are identified and cleaned up.

Bucket

Good first issue once the i18n foundation exists