The runner closed every new launch as soon as it found an Icarus window,
but app_links only forwards a lone URI with a scheme. Double-clicking an
.ica file while Icarus was open did nothing, and a launch with its own
--hive-store-dir could not start beside another Icarus. Only an icarus://
link is handed to the running window natively now; every other launch
reaches Dart's per-store single-instance check, as it did in 4.6.3.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>