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/ui/src/components/FormSection.tsx

@@ -0,0 +1,65 @@
+/*
+ * 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/>.
+ */
+
+/** @jsxRuntime automatic */
+/** @jsxImportSource hono/jsx */
+
+import type {PropsWithChildren, ReactNode} from 'hono/jsx';
+
+export type FormSectionPadding = 'none' | 'small' | 'medium' | 'large';
+
+export interface FormSectionProps {
+	title?: string;
+	bordered?: boolean;
+	padding?: FormSectionPadding;
+	children: ReactNode;
+	class?: string;
+}
+
+const paddingClasses: Record<FormSectionPadding, string> = {
+	none: '',
+	small: 'p-3',
+	medium: 'p-4',
+	large: 'p-6',
+};
+
+export function FormSection({
+	title,
+	bordered = false,
+	padding = 'medium',
+	children,
+	class: className,
+}: PropsWithChildren<FormSectionProps>) {
+	const containerClass = bordered
+		? `border border-neutral-200 rounded-lg bg-white ${paddingClasses[padding]}`
+		: paddingClasses[padding];
+
+	const content = <div class={`space-y-4 ${containerClass} ${className ?? ''}`}>{children}</div>;
+
+	if (title) {
+		return (
+			<div class={className ?? ''}>
+				<h3 class="mb-3 font-semibold text-lg text-neutral-900">{title}</h3>
+				{bordered ? content : <div class={containerClass}>{children}</div>}
+			</div>
+		);
+	}
+
+	return content;
+}