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/native_zero_copy_commands.json

@@ -0,0 +1,66 @@
+[
+	{
+		"name": "valid zero-copy native capture start",
+		"command": {
+			"type": "nativeCapture.start",
+			"operationId": 1,
+			"options": {
+				"captureId": "capture-1",
+				"source": {
+					"id": "display-1",
+					"kind": "screen",
+					"title": "Display 1",
+					"width": 1920,
+					"height": 1080,
+					"displayId": "display-1"
+				},
+				"width": 1920,
+				"height": 1080,
+				"frameRate": 60,
+				"includeCursor": true,
+				"includeAudio": false,
+				"zeroCopyRequired": true
+			}
+		},
+		"expectedOk": true
+	},
+	{
+		"name": "reject native capture start without zero-copy requirement",
+		"command": {
+			"type": "nativeCapture.start",
+			"operationId": 2,
+			"options": {
+				"captureId": "capture-2",
+				"source": {
+					"id": "window-1",
+					"kind": "window",
+					"title": "Window 1",
+					"windowId": "window-1"
+				},
+				"width": 1280,
+				"height": 720,
+				"frameRate": 60,
+				"includeCursor": true,
+				"includeAudio": false,
+				"zeroCopyRequired": false
+			}
+		},
+		"expectedOk": false,
+		"expectedError": "zeroCopyRequired"
+	},
+	{
+		"name": "reject native frame sink without zero-copy requirement",
+		"command": {
+			"type": "nativeFrameSink.attach",
+			"operationId": 3,
+			"options": {
+				"sinkId": "sink-1",
+				"captureId": "capture-1",
+				"trackSid": "TR_screen",
+				"zeroCopyRequired": false
+			}
+		},
+		"expectedOk": false,
+		"expectedError": "zeroCopyRequired"
+	}
+]