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>

test/shell.d/launch-browser-test.sh

@@ -10,6 +10,9 @@ trap 'rm -rf "$test_tmp"' EXIT
 mock_bin="$test_tmp/bin"
 test_home="$test_tmp/home"
 mkdir -p "$mock_bin" "$test_home/.local/share/applications"
+# Keep the launcher away from the running browser's singleton socket, which it
+# would otherwise hand these test URLs to.
+export XDG_CONFIG_HOME="$test_home/.config" XDG_DATA_HOME="$test_home/.local/share"
 
 cat >"$test_home/.local/share/applications/chromium.desktop" <<'EOF'
 [Desktop Entry]
@@ -79,3 +82,16 @@ grep -Fx '^chromium.*$' "$focus_log" >/dev/null ||
   fail "browser launcher focuses the browser resolved from the HTTPS handler"
 
 pass "browser launcher follows opened links to the browser workspace"
+
+rm -f "$launch_log"
+cat >"$mock_bin/omarchy-cmd-browser-handoff" <<'SH'
+#!/bin/bash
+[[ $1 == "chromium" && $2 == "https://example.test/running" ]]
+SH
+chmod +x "$mock_bin/omarchy-cmd-browser-handoff"
+
+HOME="$test_home" PATH="$mock_bin:$PATH" OMARCHY_TEST_BROWSER_LAUNCH="$launch_log" \
+  OMARCHY_TEST_BROWSER_FOCUS="$focus_log" bash "$ROOT/bin/omarchy-launch-browser" "https://example.test/running"
+
+[[ ! -e $launch_log ]] || fail "browser launcher starts no browser when the running one takes the URL"
+pass "browser launcher hands a URL to the running browser"