fix(terminal): handle Ctrl+C/V for copy & paste on Windows/Linux

On non-Mac platforms, let xterm.js ClipboardAddon handle Ctrl+C (copy
when text is selected) and Ctrl+V (paste) instead of sending control
codes to the PTY.

Closes #175

packages/app/src/terminal/runtime/terminal-emulator-runtime.ts

@@ -72,6 +72,11 @@ declare global {
   }
 }
 
+const isMac =
+  typeof navigator !== "undefined" &&
+  (/Macintosh|Mac OS/i.test(navigator.userAgent ?? "") ||
+    /Mac/i.test((navigator as any).platform ?? ""));
+
 const DEFAULT_TOUCH_SCROLL_LINE_HEIGHT_PX = 18;
 const FIT_TIMEOUT_DELAYS_MS = [0, 16, 48, 120, 250, 500, 1_000, 2_000];
 const OUTPUT_OPERATION_TIMEOUT_MS = 5_000;
@@ -280,6 +285,10 @@ export class TerminalEmulatorRuntime {
         return true;
       }
 
+      if (!isMac && event.ctrlKey && !event.shiftKey && !event.altKey && !event.metaKey) {
+        return true;
+      }
+
       const normalizedKey = normalizeDomTerminalKey(event.key);
       if (!normalizedKey || isTerminalModifierDomKey(event.key)) {
         return true;