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>

database/models.py

@@ -330,6 +330,7 @@ class Glossary(Base):
         String(36), ForeignKey("users.id", ondelete="CASCADE"), nullable=False
     )
     name = Column(String(255), nullable=False)
+    source_language = Column(String(10), nullable=False, default="fr")
     created_at = Column(DateTime, default=_utcnow)
     updated_at = Column(DateTime, default=_utcnow, onupdate=_utcnow)
 
@@ -346,6 +347,7 @@ class Glossary(Base):
             "id": self.id,
             "user_id": self.user_id,
             "name": self.name,
+            "source_language": self.source_language,
             "terms": [term.to_dict() for term in self.terms] if self.terms else [],
             "created_at": self.created_at.isoformat() if self.created_at else None,
             "updated_at": self.updated_at.isoformat() if self.updated_at else None,
@@ -365,6 +367,7 @@ class GlossaryTerm(Base):
     )
     source = Column(String(500), nullable=False)
     target = Column(String(500), nullable=False)
+    translations = Column(JSON, nullable=True, default=dict)
     created_at = Column(DateTime, default=_utcnow)
 
     # Relationship
@@ -378,6 +381,7 @@ class GlossaryTerm(Base):
             "id": self.id,
             "source": self.source,
             "target": self.target,
+            "translations": self.translations or {},
             "created_at": self.created_at.isoformat() if self.created_at else None,
         }