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>

web/package.json

@@ -16,6 +16,7 @@
     "@xterm/addon-webgl": "^0.20.0-beta.202",
     "@xterm/xterm": "^6.1.0-beta.203",
     "lucide-react": "^1.8.0",
+    "mermaid": "^11.14.0",
     "react": "^19.2.5",
     "react-dom": "^19.2.5"
   },