feat: implement web terminal feature with xterm.js and Socket.IO proxy

- Add CLI-side terminal management via Bun.Terminal with TerminalManager
- Implement server-side Socket.IO proxy for terminal I/O between web and CLI
- Create web terminal UI component with xterm.js and support for resize/reconnect
- Add terminal route and navigation button in session chat
- Include comprehensive terminal implementation plan and architecture docs

web/package.json

@@ -14,6 +14,9 @@
         "@assistant-ui/react-markdown": "^0.11.8",
         "@radix-ui/react-dialog": "^1.1.2",
         "@radix-ui/react-slot": "^1.2.0",
+        "@xterm/addon-fit": "^0.10.0",
+        "@xterm/addon-web-links": "^0.11.0",
+        "@xterm/xterm": "^5.5.0",
         "@shikijs/langs": "^3.20.0",
         "@shikijs/themes": "^3.20.0",
         "@tanstack/react-query": "^5.71.10",
@@ -28,6 +31,7 @@
         "react-textarea-autosize": "^8.5.9",
         "remark-gfm": "^4.0.1",
         "shiki": "^3.20.0",
+        "socket.io-client": "^4.8.1",
         "tailwind-merge": "^2.5.5"
     },
     "devDependencies": {