Add native self-hosted instance connection to fluxer_desktop

Trimmed monorepo checkout (fluxer_desktop + packages/voice_engine_v2 +
tools/ci) with a "Connect to a Different Server" menu item and popout
that lets the desktop app switch to any self-hosted Fluxer instance,
plus fixes for well-known discovery on single-domain self-hosted
deployments and a false-positive ERR_ABORTED on same-origin client
redirects during the switch. Defaults to chat.fluxr.chat and uses an
isolated userData directory from the official build.

fluxer_desktop/native/webrtc-sender/vendor/webrtc-sys/libwebrtc/.gclient

@@ -0,0 +1,9 @@
+solutions = [
+  {
+    "name": 'src',
+    "url": 'https://github.com/webrtc-sdk/webrtc.git@m144_release',
+    "custom_deps": {},
+    "deps_file": "DEPS",
+    "managed": False,
+  },
+]