feat: add fluxer upstream source and self-hosting documentation

- Clone of github.com/fluxerapp/fluxer (official upstream)
- SELF_HOSTING.md: full VM rebuild procedure, architecture overview,
  service reference, step-by-step setup, troubleshooting, seattle reference
- dev/.env.example: all env vars with secrets redacted and generation instructions
- dev/livekit.yaml: LiveKit config template with placeholder keys
- fluxer-seattle/: existing seattle deployment setup scripts

fluxer/packages/schema/src/domains/download/DownloadSchemas.tsx

@@ -0,0 +1,130 @@
+/*
+ * Copyright (C) 2026 Fluxer Contributors
+ *
+ * This file is part of Fluxer.
+ *
+ * Fluxer is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Fluxer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Fluxer. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import {createNamedStringLiteralUnion, withOpenApiType} from '@fluxer/schema/src/primitives/SchemaPrimitives';
+import {z} from 'zod';
+
+export const DesktopChannelEnum = withOpenApiType(
+	createNamedStringLiteralUnion(
+		[
+			['stable', 'Stable', 'The stable release channel for production use'],
+			['canary', 'Canary', 'The canary release channel for early access to new features'],
+		],
+		'The release channel',
+	),
+	'DesktopChannel',
+);
+export type DesktopChannel = z.infer<typeof DesktopChannelEnum>;
+
+export const DesktopPlatformEnum = withOpenApiType(
+	createNamedStringLiteralUnion(
+		[
+			['win32', 'Windows', 'Microsoft Windows operating system'],
+			['darwin', 'macOS', 'Apple macOS operating system'],
+			['linux', 'Linux', 'Linux operating system'],
+		],
+		'The operating system platform',
+	),
+	'DesktopPlatform',
+);
+export type DesktopPlatform = z.infer<typeof DesktopPlatformEnum>;
+
+export const DesktopArchEnum = withOpenApiType(
+	createNamedStringLiteralUnion(
+		[
+			['x64', 'x64', '64-bit x86 architecture (Intel/AMD)'],
+			['arm64', 'ARM64', '64-bit ARM architecture (Apple Silicon, ARM processors)'],
+		],
+		'The CPU architecture',
+	),
+	'DesktopArch',
+);
+export type DesktopArch = z.infer<typeof DesktopArchEnum>;
+
+export const DesktopFormatEnum = withOpenApiType(
+	createNamedStringLiteralUnion(
+		[
+			['setup', 'Setup', 'Windows installer executable'],
+			['dmg', 'DMG', 'macOS disk image'],
+			['zip', 'ZIP', 'Compressed archive'],
+			['appimage', 'AppImage', 'Linux portable application'],
+			['deb', 'DEB', 'Debian/Ubuntu package'],
+			['rpm', 'RPM', 'Red Hat/Fedora package'],
+			['tar_gz', 'TAR.GZ', 'Compressed tarball archive'],
+		],
+		'The package format',
+	),
+	'DesktopFormat',
+);
+export type DesktopFormat = z.infer<typeof DesktopFormatEnum>;
+
+export const VersionString = z
+	.string()
+	.regex(/^\d+\.\d+\.\d+$/u)
+	.describe('Semantic version string');
+
+export const DesktopRedirectParam = z.object({
+	channel: DesktopChannelEnum,
+	plat: DesktopPlatformEnum,
+	arch: DesktopArchEnum,
+	format: DesktopFormatEnum,
+});
+export type DesktopRedirectParam = z.infer<typeof DesktopRedirectParam>;
+
+export const DesktopVersionedRedirectParam = z.object({
+	channel: DesktopChannelEnum,
+	plat: DesktopPlatformEnum,
+	arch: DesktopArchEnum,
+	version: VersionString,
+	format: DesktopFormatEnum,
+});
+export type DesktopVersionedRedirectParam = z.infer<typeof DesktopVersionedRedirectParam>;
+
+export const DesktopVersionsParam = z.object({
+	channel: DesktopChannelEnum,
+	plat: DesktopPlatformEnum,
+	arch: DesktopArchEnum,
+});
+export type DesktopVersionsParam = z.infer<typeof DesktopVersionsParam>;
+
+export const DesktopVersionsQuery = z.object({
+	limit: z.coerce.number().int().min(1).max(100).default(25).describe('Maximum number of versions to return'),
+	before: VersionString.optional().describe('Return versions before this version'),
+	after: VersionString.optional().describe('Return versions after this version'),
+});
+export type DesktopVersionsQuery = z.infer<typeof DesktopVersionsQuery>;
+
+export const VersionFileResponse = z.object({
+	url: z.string().describe('Download URL for this file'),
+	sha256: z.string().nullable().describe('SHA-256 hash of the file for verification'),
+});
+export type VersionFileResponse = z.infer<typeof VersionFileResponse>;
+
+export const VersionInfoResponse = z.object({
+	version: z.string().describe('Semantic version string (e.g., 1.0.0)'),
+	pub_date: z.string().describe('ISO 8601 date when this version was published'),
+	files: z.record(DesktopFormatEnum, VersionFileResponse).describe('Map of package format to download files'),
+});
+export type VersionInfoResponse = z.infer<typeof VersionInfoResponse>;
+
+export const DesktopVersionsResponse = z.object({
+	versions: z.array(VersionInfoResponse).max(100).describe('Array of available versions'),
+	has_more: z.boolean().describe('Whether more versions are available to fetch'),
+});
+export type DesktopVersionsResponse = z.infer<typeof DesktopVersionsResponse>;