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/audio-timing/benches/smoother.rs

@@ -0,0 +1,84 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use std::hint::black_box;
+
+use criterion::{Criterion, criterion_group, criterion_main};
+use fluxer_audio_timing::{AudioTimingSmoother, SmootherInput, SourceGainRamp, StaleSourceTracker};
+
+const SR: u32 = 48_000;
+
+const FRAMES_PER_TICK: u32 = 960;
+
+const PERIOD_NS: u64 = 20_000_000;
+
+fn bench_smoother_steady_snap(c: &mut Criterion) {
+    let mut group = c.benchmark_group("audio_timing_smoother");
+    group.sample_size(100);
+    group.bench_function("snap_steady_state", |b| {
+        let mut s = AudioTimingSmoother::new(1, SR).expect("ok");
+        let _ = s
+            .adjust(SmootherInput {
+                media_ts_ns: 0,
+                frames: FRAMES_PER_TICK,
+                wall_ns: 0,
+            })
+            .expect("ok");
+        let mut n: u64 = 1;
+        b.iter(|| {
+            let result = s
+                .adjust(SmootherInput {
+                    media_ts_ns: n * PERIOD_NS,
+                    frames: FRAMES_PER_TICK,
+                    wall_ns: n * PERIOD_NS,
+                })
+                .expect("ok");
+            n = n.wrapping_add(1);
+            black_box(result);
+        });
+    });
+    group.finish();
+}
+
+fn bench_ramp_advance(c: &mut Criterion) {
+    let mut group = c.benchmark_group("audio_timing_ramp");
+    group.sample_size(100);
+    group.bench_function("advance_and_query_gain", |b| {
+        let mut r = SourceGainRamp::new();
+        b.iter(|| {
+            r.advance_tick();
+            let g = r.current_gain_q15();
+            if r.is_complete() {
+                r.reset();
+            }
+            black_box(g);
+        });
+    });
+    group.finish();
+}
+
+fn bench_stale_check(c: &mut Criterion) {
+    let mut group = c.benchmark_group("audio_timing_eviction");
+    group.sample_size(100);
+    group.bench_function("is_stale_lookup", |b| {
+        let mut t = StaleSourceTracker::new(16).expect("ok");
+        for n in 1..=16u64 {
+            t.register_source(n, n * 1_000).expect("ok");
+        }
+        let threshold = 5_000_000_000u64;
+        let mut now: u64 = 1_000_000_000;
+        b.iter(|| {
+            let stale = t.is_stale(8, now, threshold).expect("ok");
+            now = now.wrapping_add(PERIOD_NS);
+            black_box(stale);
+        });
+    });
+    group.finish();
+}
+
+criterion_group!(
+    benches,
+    bench_smoother_steady_snap,
+    bench_ramp_advance,
+    bench_stale_check
+);
+criterion_main!(benches);