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/pid_payload.rs

@@ -0,0 +1,12 @@
+#![no_main]
+
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use fluxer_desktop_native::linux_portals::pid_payload::parse_shell_eval_pid_payload;
+use libfuzzer_sys::fuzz_target;
+
+fuzz_target!(|data: &[u8]| {
+    if let Ok(payload) = std::str::from_utf8(data) {
+        let _ = parse_shell_eval_pid_payload(payload);
+    }
+});