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.

packages/voice_engine_v2/fixtures/policies/native_participant_volume.json

@@ -0,0 +1,37 @@
+[
+	{
+		"name": "local mute wins",
+		"input": {"userVolumePercent": 200, "outputVolumePercent": 100, "locallyMuted": true},
+		"expected": 0
+	},
+	{
+		"name": "unity gain",
+		"input": {"userVolumePercent": 100, "outputVolumePercent": 100, "locallyMuted": false},
+		"expected": 1
+	},
+	{
+		"name": "max user volume reaches ceiling",
+		"input": {"userVolumePercent": 200, "outputVolumePercent": 100, "locallyMuted": false},
+		"expected": 2
+	},
+	{
+		"name": "quiet participant below unity",
+		"input": {"userVolumePercent": 50, "outputVolumePercent": 100, "locallyMuted": false},
+		"expectedRange": {"minExclusive": 0, "maxExclusive": 1}
+	},
+	{
+		"name": "zero composed volume",
+		"input": {"userVolumePercent": 0, "outputVolumePercent": 100, "locallyMuted": false},
+		"expected": 0
+	},
+	{
+		"name": "non finite values fall back to unity inputs",
+		"input": {"userVolumePercent": null, "outputVolumePercent": null, "locallyMuted": false},
+		"expected": 1
+	},
+	{
+		"name": "oversized values clamp to native range",
+		"input": {"userVolumePercent": 999, "outputVolumePercent": 999, "locallyMuted": false},
+		"expectedRange": {"minInclusive": 0, "maxInclusive": 2}
+	}
+]