feat: add source/target language selectors to edit glossary dialog

Users can now change the language pair when editing a glossary:
- EditGlossaryDialog has source/target language dropdowns
- Default target_language changed from 'en' to 'multi' in create dialog
- onSave passes source_language and target_language to the backend
- Backend PATCH endpoint already supports updating these fields

Also fixes:
- CreateGlossaryDialog defaults to 'multi' instead of 'en'
- SUPPORTED_LANGUAGES now includes 'multi' option for target

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

frontend/src/app/dashboard/glossaries/CreateGlossaryDialog.tsx

@@ -292,7 +292,7 @@ export function CreateGlossaryDialog({
   const [name, setName] = useState('');
   const [nameAutoFilled, setNameAutoFilled] = useState(false);
   const [sourceLanguage, setSourceLanguage] = useState('fr');
-  const [targetLanguage, setTargetLanguage] = useState('en');
+  const [targetLanguage, setTargetLanguage] = useState('multi');
   const [terms, setTerms] = useState<GlossaryTermInput[]>([{ source: '', target: '' }]);
   const [fileTerms, setFileTerms] = useState<GlossaryTermInput[]>([]);
   const [selectedTemplate, setSelectedTemplate] = useState<GlossaryTemplate | null>(null);
@@ -305,7 +305,7 @@ export function CreateGlossaryDialog({
     setName('');
     setNameAutoFilled(false);
     setSourceLanguage('fr');
-    setTargetLanguage('en');
+    setTargetLanguage('multi');
     setTerms([{ source: '', target: '' }]);
     setFileTerms([]);
     setSelectedTemplate(null);

frontend/src/app/dashboard/glossaries/EditGlossaryDialog.tsx

@@ -17,13 +17,13 @@ import { TermEditor } from './TermEditor';
 import { exportGlossaryToCsv, parseCsvToTerms } from './csvUtils';
 import { useToast } from '@/components/ui/toast';
 import type { Glossary, GlossaryTermInput } from './types';
-import { MAX_TERMS_PER_GLOSSARY } from './types';
+import { MAX_TERMS_PER_GLOSSARY, SUPPORTED_LANGUAGES } from './types';
 
 interface EditGlossaryDialogProps {
   open: boolean;
   onOpenChange: (open: boolean) => void;
   glossary: Glossary | null;
-  onSave: (id: string, data: { name: string; terms: GlossaryTermInput[] }) => Promise<void>;
+  onSave: (id: string, data: { name: string; source_language: string; target_language: string; terms: GlossaryTermInput[] }) => Promise<void>;
   isSaving: boolean;
 }
 
@@ -35,6 +35,8 @@ export function EditGlossaryDialog({
   isSaving,
 }: EditGlossaryDialogProps) {
   const [name, setName] = useState('');
+  const [sourceLanguage, setSourceLanguage] = useState('fr');
+  const [targetLanguage, setTargetLanguage] = useState('multi');
   const [terms, setTerms] = useState<GlossaryTermInput[]>([]);
   const fileInputRef = useRef<HTMLInputElement>(null);
 
@@ -42,6 +44,8 @@ export function EditGlossaryDialog({
 
   if (glossary && !isInitialized.current) {
     setName(glossary.name);
+    setSourceLanguage(glossary.source_language || 'fr');
+    setTargetLanguage(glossary.target_language || 'multi');
     setTerms(glossary.terms.map(t => ({ source: t.source, target: t.target })));
     isInitialized.current = true;
   }
@@ -57,9 +61,11 @@ export function EditGlossaryDialog({
     
     await onSave(glossary.id, {
       name: name.trim(),
+      source_language: sourceLanguage,
+      target_language: targetLanguage,
       terms: validTerms,
     });
-  }, [glossary, name, terms, onSave]);
+  }, [glossary, name, sourceLanguage, targetLanguage, terms, onSave]);
 
   const handleExport = useCallback(() => {
     if (!glossary) return;
@@ -154,6 +160,36 @@ export function EditGlossaryDialog({
             />
           </div>
 
+          <div className="flex items-center gap-2">
+            <div className="flex-1">
+              <Label className="text-xs text-muted-foreground mb-1 block">Langue source</Label>
+              <select
+                value={sourceLanguage}
+                onChange={e => setSourceLanguage(e.target.value)}
+                disabled={isSaving}
+                className="w-full h-9 rounded-md border border-input bg-background px-3 text-sm focus:outline-none focus:ring-2 focus:ring-ring"
+              >
+                {SUPPORTED_LANGUAGES.filter(l => l.code !== 'multi').map(l => (
+                  <option key={l.code} value={l.code}>{l.flag} {l.label}</option>
+                ))}
+              </select>
+            </div>
+            <div className="pt-5 text-muted-foreground font-bold">→</div>
+            <div className="flex-1">
+              <Label className="text-xs text-muted-foreground mb-1 block">Langue cible</Label>
+              <select
+                value={targetLanguage}
+                onChange={e => setTargetLanguage(e.target.value)}
+                disabled={isSaving}
+                className="w-full h-9 rounded-md border border-input bg-background px-3 text-sm focus:outline-none focus:ring-2 focus:ring-ring"
+              >
+                {SUPPORTED_LANGUAGES.map(l => (
+                  <option key={l.code} value={l.code}>{l.flag} {l.label}</option>
+                ))}
+              </select>
+            </div>
+          </div>
+
           <div className="space-y-2">
             <Label>Terms ({validTermsCount} valid)</Label>
             <TermEditor

frontend/src/app/dashboard/glossaries/page.tsx

@@ -185,7 +185,7 @@ export default function GlossariesPage() {
     }
   };
 
-  const handleSaveGlossary = async (id: string, data: { name: string; terms: GlossaryTermInput[] }) => {
+  const handleSaveGlossary = async (id: string, data: { name: string; source_language: string; target_language: string; terms: GlossaryTermInput[] }) => {
     try {
       await updateGlossary(id, data);
       setEditDialogOpen(false);