fix: increase terminal lineHeight to 1.2 for mobile font metrics

Mobile devices use different monospace fonts (Courier on iOS, Droid Sans Mono
on Android) with larger ascent/descent metrics than desktop fonts. With
lineHeight: 1.0, calculated cell height was smaller than actual glyph height,
causing block characters to render at ~3/4 height. Increasing to 1.2 gives
mobile fonts proper vertical space while maintaining desktop compatibility.

Quality gates: TypeScript check passed, production build successful

apps/web/src/components/terminal.tsx

@@ -214,7 +214,7 @@ export const TerminalComponent: React.FC<TerminalProps> = ({
       cursorBlink: true,
       fontSize: currentFontSize,
       fontFamily: 'Menlo, Monaco, "Courier New", monospace',
-      lineHeight: 1.0,
+      lineHeight: 1.2,
       letterSpacing: 0,
       allowTransparency: false,
       theme: {