feat: store-scoped enrichment with locale-aware system prompts (#12)

[DavidLambauer]

Summary

Fixes #12. Supersedes #53 (which was the Phase 2 bundle of locale + enrichment-flags; Ryan's #51 already covers the flags half, so this PR is just the locale half, cleanly rebased onto the post-merge main).

The enrichment pipeline now carries store context end-to-end, and the AI is automatically instructed to reply in the store's language.

Changes

Store context plumbing:

• Request DTO gains a storeId field (defaults to 0 for backward compatibility with in-flight queue messages)
• Publisher::execute accepts and passes storeId to queue messages
• Consumer sets the correct store scope via StoreManager::setCurrentStore before loading the product
• SaveAfter observer forwards the product's store ID to the publisher
• MassEnrich controller forwards the current admin store scope

Locale-aware system prompt:

• Config::getSystemPrompt() now queries with SCOPE_STORE, reads general/locale/code, and prepends "Respond in {Language}. " for non-English locales
• Ships a LOCALE_LANGUAGE_MAP covering 46 ISO language codes
• English locales get the prompt unchanged; unknown locales fall through silently

Module sequence: added Magento_Store so DI resolution is ordered correctly.

Test plan

• Unit tests: 152 tests, 319 assertions, green on PHP 8.2/8.3/8.4 (via CI)
• On a non-English store (e.g., fr_FR), enrich a product: AI output should be in French
• On an English store, enrich a product: behavior identical to before
• Mass enrich from admin grid: products inherit the current admin store scope in the queue message
• Async mode: queue worker picks up the message, sets store scope before saving the product, output is correctly scoped

What changed vs the original #53

• Dropped all #48 enrichment-flags commits (Ryan's Flag enriched product attributes on product edit (#48) #51 covers the UI and Add enrichment review, caching, and approval workflow (#28) #46 covers the log table)
• Dropped the Phase 1 commits that were superseded by Ryan's Improve advanced setting info #38/Make enrichment attributes configurable (#27) #45 and the CI baseline
• Dropped the internal planning docs under docs/plans/
• Rebased cleanly onto current main; 11 files changed vs 36 before, +129/-39 lines