[FEATURE] Buddy speech bubbles should respect the user's configured language

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Non-English speaking users who configure Claude Code's language setting (e.g., "language": "es") get a split experience: Claude's responses follow the configured language correctly, but the /buddy companion's speech bubbles remain hardcoded in English. This breaks the immersion and creates unnecessary cognitive context-switching for users who work entirely in their native language. The buddy is meant to be a friendly, personal companion — but it feels disconnected when it speaks a language the user didn't choose.

Proposed Solution

The buddy's speech bubble text should follow the same language setting already available in settings.json or ~/.claude/settings.json. No new UI is strictly needed — just pass the existing language preference to the buddy's text generation layer.

Ideal experience:

1. User sets "language": "es" in their settings (as they already do today)
2. Claude responds in Spanish (already works)
3. Buddy speech bubbles also appear in Spanish (new behavior)

For extra flexibility, an optional buddy.locale override could allow users who want Claude in one language but their buddy in another — but this is a nice-to-have, not a requirement.

Alternative Solutions

• Workaround attempted: Adding instructions in CLAUDE.md like "respond in Spanish" — this affects Claude's responses but has zero effect on the buddy's speech bubbles since they are generated independently.
• Workaround attempted: Changing system locale ($LANG=es_ES.UTF-8) — no effect on buddy text.
• No viable workaround exists today. The buddy's language is not user-configurable by any means.

Priority

Medium - Would be very helpful

Feature Category

Configuration and settings

Use Case Example

Step-by-step scenario:

1. I'm a Spanish-speaking developer in Ecuador. My settings.json has "language": "es".
2. I launch Claude Code. Claude greets me in Spanish. Everything feels natural.
3. I run /buddy. My penguin companion hatches with a cute animation — great.
4. As I work, the buddy comments in its speech bubble: "Hmm, interesting approach!" or "Nice commit!" — all in English.
5. I have to mentally switch languages every time the bubble pops up. It feels like my assistant speaks my language but my pet doesn't know me.
6. Expected: The buddy would say "¡Hmm, enfoque interesante!" or "¡Buen commit!" — matching the language I already configured.

This applies equally to all 18 buddy species and every non-English language Claude Code supports.

Additional Context

• Related issue: #41978 (narrower scope, focused on "Knurl companion" specifically). This request covers the entire buddy system across all 18 species.
• The language setting already exists and works for Claude's responses — the infrastructure for language preference is already in place.
• A simple implementation could just append the user's language preference to whatever prompt/template generates the buddy's speech text.
• This aligns with the broader i18n efforts tracked in #7233 and #22356.