fix: comprehensive glossary system audit — 6 critical fixes

Full audit found 18 issues across backend, frontend, and data files.
Root cause: target_language had no single source of truth — 'en' was
hardcoded as default in 6+ places while templates are actually multilingual.

Fixes applied:
- routes/glossary_routes.py: list_glossaries() fallback 'en' → 'multi'
- routes/glossary_routes.py: import reads target_lang from index.json
  (source of truth) instead of template file
- data/glossaries/*.json: all 8 template files target_lang 'en' → 'multi'
- services/glossary_service.py: get_glossary_terms() now returns
  target_language field (was missing entirely)
- schemas/glossary_schemas.py: all defaults 'en' → 'multi'
  (GlossaryCreate, GlossaryResponse, GlossaryListItem)
- useTranslationConfig.ts: only reset glossary on sourceLang change,
  not targetLang (multilingual glossaries work with any target)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

data/glossaries/ecommerce_fr_en.json

@@ -2,7 +2,7 @@
   "name": "E-commerce & Vente - Français → Anglais",
   "description": "Terminologie e-commerce et vente française vers anglaise pour boutiques en ligne, catalogues et documents commerciaux",
   "source_lang": "fr",
-  "target_lang": "en",
+  "target_lang": "multi",
   "category": "ecommerce",
   "terms": [
     {

data/glossaries/finance_fr_en.json

@@ -2,7 +2,7 @@
   "name": "Finance & Comptabilité - Français → Anglais",
   "description": "Terminologie financière et comptable française vers anglaise pour rapports annuels, bilans et documents financiers",
   "source_lang": "fr",
-  "target_lang": "en",
+  "target_lang": "multi",
   "category": "finance",
   "terms": [
     {

data/glossaries/hr_fr_en.json

@@ -2,7 +2,7 @@
   "name": "RH & Ressources Humaines - Français → Anglais",
   "description": "Terminologie des ressources humaines française vers anglaise pour contrats, politiques et documents RH",
   "source_lang": "fr",
-  "target_lang": "en",
+  "target_lang": "multi",
   "category": "hr",
   "terms": [
     {

data/glossaries/legal_fr_en.json

@@ -2,7 +2,7 @@
   "name": "Juridique - Français → Anglais",
   "description": "Terminologie juridique française vers anglaise pour contrats, statuts et documents légaux",
   "source_lang": "fr",
-  "target_lang": "en",
+  "target_lang": "multi",
   "category": "legal",
   "terms": [
     {

data/glossaries/marketing_fr_en.json

@@ -2,7 +2,7 @@
   "name": "Marketing & Communication - Français → Anglais",
   "description": "Terminologie marketing et communication française vers anglaise pour campagnes, stratégies et contenus marketing",
   "source_lang": "fr",
-  "target_lang": "en",
+  "target_lang": "multi",
   "category": "marketing",
   "terms": [
     {

data/glossaries/medical_fr_en.json

@@ -2,7 +2,7 @@
   "name": "Médical & Santé - Français → Anglais",
   "description": "Terminologie médicale française vers anglaise pour rapports médicaux, publications scientifiques et documents de santé",
   "source_lang": "fr",
-  "target_lang": "en",
+  "target_lang": "multi",
   "category": "medical",
   "terms": [
     {

data/glossaries/scientific_fr_en.json

@@ -2,7 +2,7 @@
   "name": "Scientifique & Recherche - Français → Anglais",
   "description": "Terminologie scientifique française vers anglaise pour publications, articles de recherche et thèses",
   "source_lang": "fr",
-  "target_lang": "en",
+  "target_lang": "multi",
   "category": "scientific",
   "terms": [
     {

data/glossaries/tech_fr_en.json

@@ -2,7 +2,7 @@
   "name": "Technologie / IT - Français → Anglais",
   "description": "Terminologie technique et informatique française vers anglaise pour documentation, spécifications et rapports IT",
   "source_lang": "fr",
-  "target_lang": "en",
+  "target_lang": "multi",
   "category": "technology",
   "terms": [
     {

frontend/src/app/dashboard/translate/useTranslationConfig.ts

@@ -80,10 +80,11 @@ export function useTranslationConfig(hasFile: boolean): UseTranslationConfigRetu
     }
   }, [settings.defaultTargetLanguage]); // eslint-disable-line react-hooks/exhaustive-deps
 
-  // Reset glossary selection when source or target language changes
+  // Reset glossary selection when source language changes
+  // (multilingual glossaries are compatible with any target language)
   useEffect(() => {
     setGlossaryId(null);
-  }, [sourceLang, targetLang]); // eslint-disable-line react-hooks/exhaustive-deps
+  }, [sourceLang]); // eslint-disable-line react-hooks/exhaustive-deps
 
   // Fetch available (admin-configured) providers
   useEffect(() => {

routes/glossary_routes.py

@@ -187,7 +187,7 @@ async def list_glossaries(
                     id=g.id,
                     name=g.name,
                     source_language=g.source_language or "fr",
-                    target_language=getattr(g, "target_language", None) or "en",
+                    target_language=getattr(g, "target_language", None) or "multi",
                     terms_count=len(g.terms) if g.terms else 0,
                     created_at=g.created_at,
                 )
@@ -596,8 +596,8 @@ async def import_glossary_template(
             glossary = Glossary(
                 user_id=user.id,
                 name=glossary_name,
-                source_language=template_data.get("source_lang", "fr"),
-                target_language=template_data.get("target_lang", "en"),
+                source_language=template_info.get("source_lang", template_data.get("source_lang", "fr")),
+                target_language=template_info.get("target_lang", template_data.get("target_lang", "multi")),
                 created_at=datetime.now(timezone.utc),
                 updated_at=datetime.now(timezone.utc),
             )

schemas/glossary_schemas.py

@@ -47,7 +47,7 @@ class GlossaryCreate(BaseModel):
         default="fr", max_length=10, description="Langue source (ISO code)"
     )
     target_language: str = Field(
-        default="en", max_length=10, description="Langue cible (ISO code)"
+        default="multi", max_length=10, description="Langue cible (ISO code) ou 'multi' pour multilingue"
     )
     terms: list[GlossaryTermCreate] = Field(
         default_factory=list, description="Liste des termes"
@@ -79,7 +79,7 @@ class GlossaryResponse(BaseModel):
     id: str
     name: str
     source_language: str = "fr"
-    target_language: str = "en"
+    target_language: str = "multi"
     terms: list[GlossaryTermResponse] = []
     created_at: Optional[datetime] = None
     updated_at: Optional[datetime] = None
@@ -93,7 +93,7 @@ class GlossaryListItem(BaseModel):
     id: str
     name: str
     source_language: str = "fr"
-    target_language: str = "en"
+    target_language: str = "multi"
     terms_count: int = Field(
         default=0, description="Nombre de termes dans le glossaire"
     )

services/glossary_service.py

@@ -61,6 +61,7 @@ def get_glossary_terms(glossary_id: str, user_id: str) -> Dict[str, Any]:
 
             return {
                 "source_language": glossary.source_language or "fr",
+                "target_language": getattr(glossary, "target_language", None) or "multi",
                 "terms": result,
             }