Add web terminal for remote tablet/phone access to project terminals

Adds an axum HTTP+WebSocket server that runs alongside the Tauri app,
serving a standalone xterm.js-based terminal UI accessible from any
browser on the local network. Shares the existing ExecSessionManager
via Arc-wrapped stores, with token-based authentication and automatic
session cleanup on disconnect.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/src/components/settings/SettingsPanel.tsx

@@ -8,6 +8,7 @@ import EnvVarsModal from "../projects/EnvVarsModal";
 import { detectHostTimezone } from "../../lib/tauri-commands";
 import type { EnvVar } from "../../lib/types";
 import Tooltip from "../ui/Tooltip";
+import WebTerminalSettings from "./WebTerminalSettings";
 
 export default function SettingsPanel() {
   const { appSettings, saveSettings } = useSettings();
@@ -116,6 +117,9 @@ export default function SettingsPanel() {
         </div>
       </div>
 
+      {/* Web Terminal */}
+      <WebTerminalSettings />
+
       {/* Updates section */}
       <div>
         <label className="block text-sm font-medium mb-2">Updates<Tooltip text="Check for new versions of the Triple-C app and container image." /></label>