feat(shell): dedicated System Analyst AI, no code execution, analyze system

- New ShellConvStore with persistent history (shell_conversation.json)
- 100k token limit — input grays out, must /clear to continue
- Commands limited to /clear and /help only
- Shell AI has NO tools — read-only analysis, never executes code
- "Analyste Système" panel with system analysis button
- System analysis uses Studio AI to write system_analysis.md,
  prepended as context on every conversation start
- Code blocks show "Copier" and "Terminal" buttons to copy or
  send code directly to the active terminal via WebSocket
- Token bar shows usage with warning at 80%

💘 Generated with Crush

Assisted-by: GLM-5.1 via Crush <crush@charm.land>

web/src/i18n/fr.js

@@ -136,7 +136,7 @@ const fr = {
       terminal: 'Terminal',
       updates: 'Mises \u00e0 jour',
       locale: 'Langue & Clavier',
-      skills: 'Comp\u00e9ENCES',
+      skills: 'Compétences',
       system: 'Syst\u00e8me',
     },
     profile: 'Profil',
@@ -160,7 +160,7 @@ const fr = {
     save: 'Enregistrer',
     saved: 'Enregistr\u00e9 !',
     error: 'Erreur',
-    skills: 'Comp\u00e9ENCES',
+    skills: 'Compétences',
     noSkills: 'Aucune comp\u00e9tence install\u00e9e.',
     runSkillsInit: 'Ex\u00e9cutez muyue skills init',
     language: 'Langue',