Hand browser and web app launches to the running browser directly (#13530)

* Hand browser and web app launches to the running browser directly

With a Chromium-based browser already running, each launch started a second
browser process only to pass its command line over the profile's singleton
socket and exit, ~165ms before the running browser even heard of it.
omarchy-cmd-browser-handoff sends that message itself with socat and waits
for the ACK, so a web app opens in ~210ms instead of ~430ms.

It hands off only what it can do exactly as the browser would: the packaged
browser binary rather than a wrapper, a flags file holding nothing beyond the
process flags Omarchy ships, no other data directory, and a socket we own.
Anything else, or no answer, launches the browser as before.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Hand Brave Origin launches to the running browser too

/usr/bin/brave-origin is the package's own launcher, reading
brave-origin-flags.conf, with the profile in BraveSoftware/Brave-Origin.
A web app now opens in ~158ms instead of ~345ms.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

bin/omarchy-launch-browser

@@ -14,9 +14,11 @@ else
   private_flag="--incognito"
 fi
 
-systemd-run --user --quiet --collect --unit="omarchy-browser-$(date +%s%N)" \
-  --property=StandardOutput=null --property=StandardError=null \
-  uwsm-app -- "$browser_exec" "${@/--private/$private_flag}"
+if ! omarchy-cmd-browser-handoff "$browser_exec" "${@/--private/$private_flag}"; then
+  systemd-run --user --quiet --collect --unit="omarchy-browser-$(date +%s%N)" \
+    --property=StandardOutput=null --property=StandardError=null \
+    uwsm-app -- "$browser_exec" "${@/--private/$private_flag}"
+fi
 
 url=""
 for argument in "$@"; do