feat: terminal sudo blocking, token tracking, mermaid & consumption UI

- Block sudo/doas commands when not running as root
- Add real token counting from API responses
- Track and display consumption by provider/day
- Add Mermaid diagram rendering in Shell and Studio
- Add copy-to-clipboard buttons for code blocks
- Support tables in AI message rendering
- Update system prompt with context (date, time, root status)

💘 Generated with Crush

Assisted-by: MiniMax-M2.7 via Crush <crush@charm.land>

internal/api/handlers_chat.go

@@ -3,9 +3,12 @@ package api
 import (
 	"context"
 	"encoding/json"
+	"fmt"
 	"net/http"
+	"os"
 	"regexp"
 	"strings"
+	"time"
 
 	"github.com/muyue/muyue/internal/agent"
 	"github.com/muyue/muyue/internal/orchestrator"
@@ -42,7 +45,14 @@ func (s *Server) handleChat(w http.ResponseWriter, r *http.Request) {
 		writeError(w, err.Error(), http.StatusServiceUnavailable)
 		return
 	}
-	orb.SetSystemPrompt(agent.StudioSystemPrompt())
+	var studioPrompt strings.Builder
+	studioPrompt.WriteString(agent.StudioSystemPrompt())
+	studioPrompt.WriteString(fmt.Sprintf("\nDate: %s\nHeure: %s\n", time.Now().Format("02/01/2006"), time.Now().Format("15:04:05")))
+	studioPrompt.WriteString(fmt.Sprintf("Root: %t\n", os.Geteuid() == 0))
+	if os.Geteuid() != 0 {
+		studioPrompt.WriteString("⚠️ Session utilisateur standard — les commandes sudo/doas nécessitent une autorisation. N'utilise PAS sudo ou doas sans demander.\n")
+	}
+	orb.SetSystemPrompt(studioPrompt.String())
 	orb.SetTools(s.agentToolsJSON)
 
 	if body.Stream {
@@ -91,6 +101,9 @@ func (s *Server) handleStreamChat(w http.ResponseWriter, orb *orchestrator.Orche
 		storeContent = string(storeJSON)
 	}
 	s.convStore.Add("assistant", storeContent)
+	s.convStore.AddRealTokens(engine.TotalTokens)
+
+	s.consumption.Record(engine.ProviderName(), engine.TotalTokens)
 
 	sseWriter.Write(map[string]interface{}{"done": "true"})
 }
@@ -107,6 +120,10 @@ func (s *Server) handleNonStreamChat(w http.ResponseWriter, orb *orchestrator.Or
 	}
 
 	s.convStore.Add("assistant", finalContent)
+	s.convStore.AddRealTokens(engine.TotalTokens)
+
+	s.consumption.Record(engine.ProviderName(), engine.TotalTokens)
+
 	writeJSON(w, map[string]string{"content": finalContent})
 }