fix(i18n): use i18n key for 'Parameters' label in tool call expansion

The 'Paramètres' label in ToolCall.tsx was hardcoded in French instead of
using the i18n system. Added tool.parameters key to both EN and FR locales.

src/lib/i18n.ts

@@ -47,6 +47,7 @@ const en = {
   'thinking.label': 'Thinking',
 
   // Tool call
+  'tool.parameters': 'Parameters',
   'tool.result': 'Result',
 
   // Connection banner
@@ -91,6 +92,7 @@ const fr: Record<keyof typeof en, string> = {
 
   'thinking.label': 'Réflexion',
 
+  'tool.parameters': 'Paramètres',
   'tool.result': 'Résultat',
 
   'connection.reconnecting': 'Connexion perdue — reconnexion…',