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/webrtc-sender/benches/camera_background.rs

@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use criterion::{Criterion, Throughput, criterion_group, criterion_main};
+use fluxer_webrtc_sender::bench_internals::{
+    BlurScratch, MaskRefiner, blur_plane_masked, composite_masked_plane,
+};
+use std::hint::black_box;
+
+const BENCH_WIDTH: usize = 1280;
+const BENCH_HEIGHT: usize = 720;
+const BENCH_BLUR_RADIUS_PASS: usize = 6;
+const BENCH_MASK_FEATHER_PX: usize = 64;
+
+fn synth_plane(seed: usize) -> Vec<u8> {
+    let mut plane = vec![0u8; BENCH_WIDTH * BENCH_HEIGHT];
+    for (index, value) in plane.iter_mut().enumerate() {
+        *value = ((index * 31 + seed) % 251) as u8;
+    }
+    plane
+}
+
+fn synth_person_mask() -> Vec<u8> {
+    let mut mask = vec![0u8; BENCH_WIDTH * BENCH_HEIGHT];
+    let person_edge = BENCH_WIDTH / 2;
+    for row in mask.chunks_exact_mut(BENCH_WIDTH) {
+        for (x, value) in row.iter_mut().enumerate() {
+            *value = if x < person_edge {
+                255
+            } else if x < person_edge + BENCH_MASK_FEATHER_PX {
+                (255 - (x - person_edge) * 255 / BENCH_MASK_FEATHER_PX) as u8
+            } else {
+                0
+            };
+        }
+    }
+    mask
+}
+
+fn bench_blur_plane_masked(c: &mut Criterion) {
+    let source = synth_plane(7);
+    let mask = synth_person_mask();
+    let mut plane = source.clone();
+    let mut scratch = BlurScratch::new(BENCH_WIDTH, BENCH_HEIGHT);
+
+    let mut group = c.benchmark_group("camera_background::blur_plane_masked");
+    group.throughput(Throughput::Bytes((BENCH_WIDTH * BENCH_HEIGHT) as u64));
+    group.bench_function("1280x720_radius_pass6", |b| {
+        b.iter(|| {
+            plane.copy_from_slice(&source);
+            blur_plane_masked(
+                black_box(&mut plane),
+                BENCH_WIDTH,
+                BENCH_HEIGHT,
+                black_box(&mask),
+                BENCH_BLUR_RADIUS_PASS,
+                &mut scratch,
+            );
+            black_box(&plane);
+        })
+    });
+    group.finish();
+}
+
+fn bench_mask_refine(c: &mut Criterion) {
+    let luma = synth_plane(13);
+    let raw_mask = synth_person_mask();
+    let mut mask = raw_mask.clone();
+    let mut refiner = MaskRefiner::new(BENCH_WIDTH, BENCH_HEIGHT);
+
+    let mut group = c.benchmark_group("camera_background::mask_refine");
+    group.throughput(Throughput::Bytes((BENCH_WIDTH * BENCH_HEIGHT) as u64));
+    group.bench_function("1280x720_guided_refine", |b| {
+        b.iter(|| {
+            mask.copy_from_slice(&raw_mask);
+            refiner.refine(black_box(&luma), black_box(&mut mask));
+            black_box(&mask);
+        })
+    });
+    group.finish();
+}
+
+fn bench_composite_masked_plane(c: &mut Criterion) {
+    let source = synth_plane(11);
+    let background = synth_plane(151);
+    let mask = synth_person_mask();
+    let mut plane = source.clone();
+
+    let mut group = c.benchmark_group("camera_background::composite_masked_plane");
+    group.throughput(Throughput::Bytes((BENCH_WIDTH * BENCH_HEIGHT) as u64));
+    group.bench_function("1280x720_feathered_mask", |b| {
+        b.iter(|| {
+            plane.copy_from_slice(&source);
+            composite_masked_plane(
+                black_box(&mut plane),
+                black_box(&background),
+                BENCH_WIDTH,
+                BENCH_HEIGHT,
+                &mask,
+            );
+            black_box(&plane);
+        })
+    });
+    group.finish();
+}
+
+criterion_group!(
+    benches,
+    bench_blur_plane_masked,
+    bench_mask_refine,
+    bench_composite_masked_plane
+);
+criterion_main!(benches);