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/rust/fuzz/fuzz_targets/audio_converter.rs

@@ -0,0 +1,40 @@
+#![no_main]
+
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use arbitrary::Arbitrary;
+use fluxer_desktop_native::mac_app_audio::audio_converter::{
+    AudioBuffer, AudioBufferListN, build_input_asbd, convert_buffer_list_to_interleaved_f32,
+};
+use libfuzzer_sys::fuzz_target;
+
+#[derive(Arbitrary, Debug)]
+struct Input {
+    samples: Vec<f32>,
+    sample_rate: f64,
+    output_rate: f64,
+    channels: u8,
+}
+
+fuzz_target!(|input: Input| {
+    let channels = u32::from(input.channels.clamp(1, 2));
+    let sample_rate = if input.sample_rate.is_finite() && input.sample_rate > 0.0 {
+        input.sample_rate.min(384_000.0)
+    } else {
+        48_000.0
+    };
+    let output_rate = if input.output_rate.is_finite() && input.output_rate > 0.0 {
+        input.output_rate.min(384_000.0)
+    } else {
+        48_000.0
+    };
+    let frame_count = (input.samples.len() as u32 / channels).min(4096);
+    let list = AudioBufferListN {
+        m_number_buffers: 1,
+        buffers: [AudioBuffer::from_slice(channels, &input.samples)],
+    };
+    let asbd = build_input_asbd(sample_rate, channels, false);
+    let mut out = vec![0.0_f32; frame_count as usize * 4 + 16];
+    let _ =
+        convert_buffer_list_to_interleaved_f32(asbd, &list, frame_count, output_rate, 2, &mut out);
+});