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/api/src/utils/RequestPathUtils.tsx

@@ -0,0 +1,56 @@
+/*
+ * 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/>.
+ */
+
+const VERSION_PATTERN = /^\/v\d+/;
+
+export function stripApiPrefix(path: string): string {
+	if (path === '/api') {
+		return '/';
+	}
+
+	if (path.startsWith('/api/')) {
+		const afterApi = path.slice(4);
+		if (VERSION_PATTERN.test(afterApi)) {
+			const versionMatch = afterApi.match(VERSION_PATTERN);
+			if (versionMatch) {
+				const remaining = afterApi.slice(versionMatch[0].length);
+				return remaining === '' ? '/' : remaining;
+			}
+		}
+		return afterApi;
+	}
+
+	if (VERSION_PATTERN.test(path)) {
+		const versionMatch = path.match(VERSION_PATTERN);
+		if (versionMatch) {
+			const remaining = path.slice(versionMatch[0].length);
+			return remaining === '' ? '/' : remaining;
+		}
+	}
+
+	return path;
+}
+
+export function normalizeRequestPath(path: string): string {
+	let normalized = stripApiPrefix(path);
+	if (normalized.length > 1 && normalized.endsWith('/')) {
+		normalized = normalized.slice(0, -1);
+	}
+	return normalized;
+}