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/time/src/tests/Sleep.test.tsx

@@ -0,0 +1,44 @@
+/*
+ * 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 {sleepMs} from '@fluxer/time/src/Sleep';
+import {describe, expect, it} from 'vitest';
+
+describe('sleepMs', () => {
+	it('resolves after approximately the provided duration', async () => {
+		const startMs = Date.now();
+		await sleepMs(50);
+		const elapsedMs = Date.now() - startMs;
+
+		expect(elapsedMs).toBeGreaterThanOrEqual(45);
+		expect(elapsedMs).toBeLessThan(150);
+	});
+
+	it('clamps negative durations to zero', async () => {
+		const startMs = Date.now();
+		await sleepMs(-10);
+		const elapsedMs = Date.now() - startMs;
+
+		expect(elapsedMs).toBeLessThan(50);
+	});
+
+	it('throws for non-finite inputs', () => {
+		expect(() => sleepMs(Number.POSITIVE_INFINITY)).toThrow('Invalid sleep duration milliseconds: Infinity');
+	});
+});