feat: add Obsidian CLI API service

- Add Docker image for the official Obsidian desktop app and CLI.

- Start Obsidian headlessly with Xvfb and DBus setup.

- Expose a safe structured HTTP command API without shell execution.

- Add JWT-based vault, path, and command authorization.

- Support single-vault and multi-vault container mounts.

- Add TypeScript SDK helpers for Obsidian CLI commands.

- Add n8n community node package with Obsidian operations.

- Add docs, compose config, tests, and production image workflow.

packages/n8n-nodes-obsidian-api/shared/ObsidianApiClient.ts

@@ -0,0 +1,77 @@
+import type {
+	IExecuteFunctions,
+	IDataObject,
+	IHttpRequestOptions,
+} from 'n8n-workflow';
+import { NodeOperationError } from 'n8n-workflow';
+
+export interface ObsidianCommandResult extends IDataObject {
+	id: string;
+	command: string[];
+	cwd: string;
+	exit_code: number;
+	stdout: string;
+	stderr: string;
+	duration_ms: number;
+	timed_out: boolean;
+}
+
+export interface ObsidianCredentials extends IDataObject {
+	baseUrl: string;
+	apiToken: string;
+	defaultVault?: string;
+}
+
+export function compactArgs(args: Array<string | undefined | null | false>): string[] {
+	return args.filter((arg): arg is string => typeof arg === 'string' && arg.length > 0);
+}
+
+export function kv(name: string, value: string | number | boolean | undefined | null): string | undefined {
+	if (value === undefined || value === null || value === '') return undefined;
+	if (typeof value === 'boolean') return value ? name : undefined;
+	return `${name}=${value}`;
+}
+
+export function withVault(args: string[], vault?: string): string[] {
+	if (!vault || args[0]?.startsWith('vault=')) return args;
+	return [`vault=${vault}`, ...args];
+}
+
+export async function executeObsidianCommand(
+	context: IExecuteFunctions,
+	itemIndex: number,
+	args: string[],
+	options: { vault?: string; timeout?: number; stdin?: string } = {},
+): Promise<ObsidianCommandResult> {
+	const credentials = await context.getCredentials('obsidianApi') as ObsidianCredentials;
+	const baseUrl = String(credentials.baseUrl).replace(/\/$/, '');
+	const vault = options.vault || String(credentials.defaultVault || '');
+	const finalArgs = withVault(args, vault);
+
+	const request: IHttpRequestOptions = {
+		method: 'POST',
+		url: `${baseUrl}/commands`,
+		headers: {
+			Authorization: `Bearer ${credentials.apiToken}`,
+			'Content-Type': 'application/json',
+		},
+		body: {
+			args: finalArgs,
+			stdin: options.stdin || undefined,
+			timeout: options.timeout,
+		},
+		json: true,
+	};
+
+	const result = await context.helpers.httpRequest(request) as ObsidianCommandResult;
+
+	if (result.exit_code !== 0) {
+		throw new NodeOperationError(
+			context.getNode(),
+			`Obsidian CLI command failed with exit code ${result.exit_code}: ${result.stderr || result.stdout}`,
+			{ itemIndex },
+		);
+	}
+
+	return result;
+}