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.

.gitignore

@@ -0,0 +1,115 @@
+*.tsbuildinfo
+**/*.beam
+**/*.css.d.ts
+**/*.dump
+**/dump.rdb
+**/*.iml
+**/*.log
+**/*.o
+**/*.node
+**/*.plt
+**/*.so
+**/*.so.*
+!fluxer_desktop/native/webrtc-sender/vendor/webrtc-sys/src/lazy_load_deps_for/**/*.so.init.c
+!fluxer_desktop/native/webrtc-sender/vendor/webrtc-sys/src/lazy_load_deps_for/**/*.so.tramp.S
+**/*.source
+**/*.swo
+**/*.swp
+**/*.tmp
+**/*~
+**/.*cache
+**/.cache
+**/__pycache__
+**/.dev-runner/
+**/.devenv
+.devenv.flake.nix
+devenv.local.nix
+**/.direnv
+/dev/livekit.yaml
+/dev/bluesky_oauth_key.pem
+/dev/meilisearch_master_key
+/dev/data/
+**/.dev.vars
+**/.DS_Store
+**/.env
+**/.env.*.local
+**/.env.local
+**/.erlang.cookie
+**/.eunit
+**/.idea
+**/.next
+**/.next/cache
+**/.pnp
+**/.pnp.js
+**/.pnpm-store
+**/.rebar
+**/.rebar3
+**/.source
+**/.swc
+**/.vercel
+**/_build
+**/_checkouts
+**/_vendor
+**/certificates
+**/coverage
+**/dist
+**/ebin
+**/erl_crash.dump
+/erl_crash.dump
+**/fluxer.env
+**/generated
+**/log
+**/logs
+**/node_modules
+**/npm-debug.log*
+**/out
+**/pnpm-debug.log*
+**/rebar3.crashdump
+**/secrets.env
+**/target
+**/test-results.json
+**/Thumbs.db
+**/yarn-debug.log*
+**/yarn-error.log*
+/.devserver-cache.json
+**/.devserver-cache.json
+/.fluxer/
+/scripts/remote/hosts.json
+/config/env/local.env
+/fluxer_app/src/features/ui/constants/AvatarStatusGeometry.ts
+/fluxer_app/src/features/ui/components/SVGMasks.tsx
+/fluxer_app/src/features/i18n/locales/*/messages.js
+/fluxer_app/src/features/i18n/locales/*/messages.mjs
+/fluxer_app/src/features/i18n/locales/*/messages.ts
+/fluxer_app/pkgs/libfluxcore/
+/fluxer_gateway/config/sys.config
+/fluxer_gateway/config/vm.args
+/packages/config/src/ConfigSchema.json
+/packages/config/src/MasterZodSchema.generated.tsx
+fluxer.yaml
+GEMINI.md
+geoip_data
+tmp/
+next-env.d.ts
+deploy/kubeconfig/
+/deploy/helm/**/Chart.lock
+/deploy/helm/**/charts/
+.github/agents
+.github/prompts
+
+**/public/static/app.css
+**/public/static/app.*.css
+**/public/static/tailwind.css
+**/public/static/tailwind.*.css
+
+**/zig-out/
+**/.zig-cache/
+fluxer_media_proxy/bench-results/
+fluxer_media_proxy/.benchmark-cache/
+.claude/
+
+# Generated by tools/ci build-desktop --step set_build_channel
+fluxer_desktop/src/common/BuildChannel.ts
+
+# Generated by tools/ci build-markdown-parser-wasm
+fluxer_app/src/features/messaging/utils/markdown/parser/MarkdownParserWasmBytes.ts