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/webauthn/index.d.ts

@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import type {Buffer} from 'node:buffer';
+
+export type AuthenticatorAttachment = 'platform' | 'cross-platform' | string;
+export type PublicKeyCredentialType = 'public-key';
+export type UserVerificationRequirement = 'discouraged' | 'preferred' | 'required';
+export type ResidentKeyRequirement = 'discouraged' | 'preferred' | 'required';
+export type AttestationConveyancePreference = 'direct' | 'enterprise' | 'indirect' | 'none';
+
+export interface PublicKeyCredentialDescriptor {
+	id: Buffer;
+	type: PublicKeyCredentialType;
+	transports?: ReadonlyArray<string>;
+}
+
+export interface PublicKeyCredentialCreationOptions {
+	attestation?: AttestationConveyancePreference;
+	authenticatorSelection?: {
+		authenticatorAttachment?: AuthenticatorAttachment;
+		requireResidentKey?: boolean;
+		residentKey?: ResidentKeyRequirement;
+		userVerification?: UserVerificationRequirement;
+	};
+	challenge: Buffer;
+	excludeCredentials?: ReadonlyArray<PublicKeyCredentialDescriptor>;
+	extensions?: unknown;
+	pubKeyCredParams: ReadonlyArray<{
+		alg: number;
+		type: PublicKeyCredentialType;
+	}>;
+	rp: {
+		id?: string;
+		name: string;
+	};
+	timeout?: number;
+	origin: string;
+	user: {
+		displayName: string;
+		id: Buffer;
+		name: string;
+	};
+	windowHandle?: Buffer;
+	pin?: string;
+}
+
+export interface PublicKeyCredentialRequestOptions {
+	allowCredentials?: ReadonlyArray<PublicKeyCredentialDescriptor>;
+	challenge: Buffer;
+	extensions?: unknown;
+	origin: string;
+	rpId?: string;
+	timeout?: number;
+	userVerification?: UserVerificationRequirement;
+	windowHandle?: Buffer;
+	pin?: string;
+}
+
+export interface PublicKeyCredential {
+	authenticatorAttachment?: AuthenticatorAttachment;
+	id: string;
+	rawId: Buffer;
+	response: Buffer;
+	type: PublicKeyCredentialType;
+}
+
+export interface WebAuthnBackendInfo {
+	apiVersion: number;
+	backend: 'macos-authenticationservices' | 'windows-webauthn' | 'linux-libfido2' | 'unavailable';
+	ceremoniesImplemented: boolean;
+	nativeLoaded: boolean;
+	platformAuthenticatorAvailable: boolean;
+	platformBrokerAvailable: boolean;
+	reason: string;
+	supported: boolean;
+	target: string;
+}
+
+export declare function create(options: PublicKeyCredentialCreationOptions): Promise<PublicKeyCredential>;
+
+export declare function get(options: PublicKeyCredentialRequestOptions): Promise<PublicKeyCredential>;
+
+export declare function getBackendInfo(): WebAuthnBackendInfo;
+
+export declare function isSupported(): Promise<boolean>;
+
+export declare const loadError: Error | null;