refactor: redesign Config as settings window with sidebar panels, remove system overview from Dashboard

- Config: sidebar navigation with 5 panels (Profile, AI Providers, Updates, Locale, Skills)
- Dashboard: remove duplicated system overview section, keep workflows and activity log
- New CSS for config window layout, cards, provider cards, update rows
- Add i18n panel keys (FR/EN)

💾 Generated with Crush

Assisted-by: GLM-5-Turbo via Crush <crush@charm.land>

web/src/i18n/en.js

@@ -113,6 +113,13 @@ const en = {
   },
 
   config: {
+    panels: {
+      profile: 'Profile',
+      providers: 'AI Providers',
+      updates: 'Updates',
+      locale: 'Language & Keyboard',
+      skills: 'Skills',
+    },
     profile: 'Profile',
     name: 'Name',
     pseudo: 'Pseudo',
@@ -155,7 +162,7 @@ const en = {
     version: 'Version',
     installed: 'Installed',
     missing: 'Missing',
-    editProfile: 'Edit profile',
+    editProfile: 'Edit',
     cancel: 'Cancel',
     editProvider: 'Configure',
   },