deps: upgrade ink from 6.2.0 to 6.8.0

Upgrade the Ink terminal UI framework to the latest version.

Code changes required for compatibility:
- Pass concurrent: true to inkRender() (new default behavior in 6.8.0)
- Defer unmountInk() calls with setImmediate() so React 19 can flush
  batched state updates before the component tree is torn down
- Adapt waitUntilExit() return type change (.then(() => {}))

Co-authored-by: Claude Code <claude-code@anthropic.com>

Author: isaacroldan

packages/cli-kit/package.json

@@ -139,7 +139,7 @@
     "graphql": "16.10.0",
     "graphql-request": "6.1.0",
     "ignore": "6.0.2",
-    "ink": "6.2.0",
+    "ink": "6.8.0",
     "is-executable": "2.0.1",
     "is-interactive": "2.0.0",
     "is-wsl": "3.1.0",

packages/cli-kit/src/private/node/testing/ui.ts

@@ -81,7 +81,7 @@ export const render = (tree: ReactElement, options: RenderOptions = {}): Instanc
     rerender: instance.rerender,
     unmount: instance.unmount,
     cleanup: instance.cleanup,
-    waitUntilExit: () => trackPromise(instance.waitUntilExit()),
+    waitUntilExit: () => trackPromise(instance.waitUntilExit().then(() => {})),
     stdout,
     stderr,
     stdin,