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/markdown_parser/src/parser/Parser.tsx

@@ -0,0 +1,35 @@
+/*
+ * 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 {parseMarkdownAst} from '@fluxer/markdown_parser/src/parser/ParserEngine';
+import type {Node} from '@fluxer/markdown_parser/src/types/Nodes';
+
+export class Parser {
+	private readonly input: string;
+	private readonly parserFlags: number;
+
+	constructor(input: string, flags: number) {
+		this.input = input;
+		this.parserFlags = flags;
+	}
+
+	parse(): {nodes: Array<Node>} {
+		return parseMarkdownAst(this.input, this.parserFlags);
+	}
+}