feat: add multilingual glossary support (backend + frontend types)

Backend:
- Add source_language column to glossaries table
- Add translations JSON column to glossary_terms table
- Alembic migration for schema changes
- format_glossary_for_prompt now language-aware: extracts correct
  translation per target language, falls back to EN reference for
  templates with only FR→EN data
- CRUD routes accept/return source_language and translations
- Pydantic schemas updated

Frontend:
- Types updated: GlossaryTerm now has translations: Record<string, string>
- Glossary/GlossaryListItem now have source_language
- Added SUPPORTED_LANGUAGES constant (13 languages)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

routes/translate_routes.py

@@ -915,10 +915,13 @@ async def _run_translation_job(
 
         # Story 3.10: Retrieve and format glossary terms for LLM prompt
         glossary_terms = None
+        glossary_source_lang = "fr"
         if glossary_id and user_id:
             try:
-                glossary_terms = get_glossary_terms(glossary_id, user_id)
-                logger.info(f"Job {job_id}: Loaded {len(glossary_terms)} glossary terms")
+                glossary_data = get_glossary_terms(glossary_id, user_id)
+                glossary_terms = glossary_data["terms"]
+                glossary_source_lang = glossary_data.get("source_language", "fr")
+                logger.info(f"Job {job_id}: Loaded {len(glossary_terms)} glossary terms (source: {glossary_source_lang})")
             except GlossaryNotFoundError as e:
                 tracker.set_error(str(e))
                 logger.error(f"Job {job_id}: Glossary error - {e}")
@@ -940,7 +943,10 @@ async def _run_translation_job(
             effective_prompt = custom_prompt
 
         # Build the full prompt combining effective prompt and glossary
-        full_prompt = build_full_prompt(effective_prompt, glossary_terms)
+        full_prompt = build_full_prompt(
+            effective_prompt, glossary_terms,
+            source_lang=glossary_source_lang, target_lang=target_lang,
+        )
 
         translation_provider = None
         _p = provider.lower()