chore: update terminal theme to match ghostty-web demo

- Use JetBrains Mono font (with Menlo/Monaco fallbacks)
- Increase font size from 13 to 14
- Simplify theme to just background/foreground (use defaults for colors)

Author: sreya

src/browser/components/TerminalView.tsx

@@ -82,31 +82,12 @@ export function TerminalView({ workspaceId, sessionId, visible }: TerminalViewPr
         await init();
 
         terminal = new Terminal({
-          fontSize: 13,
-          fontFamily: "Monaco, Menlo, 'Courier New', monospace",
+          fontSize: 14,
+          fontFamily: "JetBrains Mono, Menlo, Monaco, monospace",
           cursorBlink: true,
           theme: {
             background: "#1e1e1e",
             foreground: "#d4d4d4",
-            cursor: "#d4d4d4",
-            cursorAccent: "#1e1e1e",
-            selectionBackground: "#264f78",
-            black: "#000000",
-            red: "#cd3131",
-            green: "#0dbc79",
-            yellow: "#e5e510",
-            blue: "#2472c8",
-            magenta: "#bc3fbc",
-            cyan: "#11a8cd",
-            white: "#e5e5e5",
-            brightBlack: "#666666",
-            brightRed: "#f14c4c",
-            brightGreen: "#23d18b",
-            brightYellow: "#f5f543",
-            brightBlue: "#3b8eea",
-            brightMagenta: "#d670d6",
-            brightCyan: "#29b8db",
-            brightWhite: "#ffffff",
           },
         });