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/fluxer_app_proxy/src/Config.tsx

@@ -0,0 +1,38 @@
+/*
+ * 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 {loadConfig} from '@fluxer/config/src/ConfigLoader';
+import {extractBaseServiceConfig} from '@fluxer/config/src/ServiceConfigSlices';
+
+const master = await loadConfig();
+const appProxy = master.services.app_proxy;
+
+if (!appProxy) {
+	throw new Error('Application proxy requires `services.app_proxy` configuration');
+}
+
+export const Config = {
+	...extractBaseServiceConfig(master),
+	port: appProxy.port,
+	static_cdn_endpoint: appProxy.static_cdn_endpoint,
+	sentry_dsn: master.app_public.sentry_dsn,
+	assets_dir: appProxy.assets_dir,
+};
+
+export type Config = typeof Config;

fluxer/fluxer_app_proxy/src/Instrument.tsx

@@ -0,0 +1,26 @@
+/*
+ * 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 {Config} from '@app/Config';
+import {createServiceInstrumentation} from '@fluxer/initialization/src/CreateServiceInstrumentation';
+
+export const shutdownInstrumentation = createServiceInstrumentation({
+	serviceName: 'fluxer-app-proxy',
+	config: Config,
+});

fluxer/fluxer_app_proxy/src/Logger.tsx

@@ -0,0 +1,23 @@
+/*
+ * 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 {createLogger, type Logger as FluxerLogger} from '@fluxer/logger/src/Logger';
+
+export const Logger = createLogger('fluxer-app-proxy');
+export type Logger = FluxerLogger;

fluxer/fluxer_app_proxy/src/index.tsx

@@ -0,0 +1,66 @@
+/*
+ * 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 {Config} from '@app/Config';
+import {shutdownInstrumentation} from '@app/Instrument';
+import {Logger} from '@app/Logger';
+import {createAppProxyApp} from '@fluxer/app_proxy/src/App';
+import {buildFluxerCSPOptions} from '@fluxer/app_proxy/src/app_server/utils/CSP';
+import {createServiceTelemetry} from '@fluxer/hono/src/middleware/TelemetryAdapters';
+import {createServer, setupGracefulShutdown} from '@fluxer/hono/src/Server';
+
+const telemetry = createServiceTelemetry({
+	serviceName: 'fluxer-app-proxy',
+	skipPaths: ['/_health'],
+});
+
+async function main(): Promise<void> {
+	const cspDirectives = buildFluxerCSPOptions({sentryDsn: Config.sentry_dsn});
+
+	const {app, shutdown} = await createAppProxyApp({
+		config: Config,
+		cspDirectives,
+		logger: Logger,
+		metricsCollector: telemetry.metricsCollector,
+		staticCDNEndpoint: Config.static_cdn_endpoint,
+		staticDir: Config.assets_dir,
+		tracing: telemetry.tracing,
+	});
+
+	const port = Config.port;
+	Logger.info({port}, 'Starting Fluxer App Proxy');
+
+	const server = createServer(app, {port});
+
+	setupGracefulShutdown(
+		async () => {
+			await shutdown();
+			await shutdownInstrumentation();
+			await new Promise<void>((resolve) => {
+				server.close(() => resolve());
+			});
+		},
+		{logger: Logger},
+	);
+}
+
+main().catch((err) => {
+	Logger.fatal({error: err}, 'fatal error');
+	process.exit(1);
+});