Initial release: n8n Plex Media Server node

Features:
- Server: Get identity, info, preferences, sessions, butler tasks
- Library: Get all, get contents, recently added, on deck, refresh, analyze
- Media: Get, update, delete, refresh, mark watched/unwatched
- Playlist: CRUD operations, add/remove items
- Collection: CRUD operations, add/remove items
- Search: Global and library-specific search
- Session: Get active sessions, history, terminate

Includes CI/CD pipeline for automatic npm publishing on release.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

credentials/PlexApi.credentials.ts

@@ -0,0 +1,85 @@
+import {
+	IAuthenticateGeneric,
+	ICredentialTestRequest,
+	ICredentialType,
+	INodeProperties,
+} from 'n8n-workflow';
+
+export class PlexApi implements ICredentialType {
+	name = 'plexApi';
+	displayName = 'Plex API';
+	documentationUrl = 'https://developer.plex.tv/pms/';
+	properties: INodeProperties[] = [
+		{
+			displayName: 'Server URL',
+			name: 'serverUrl',
+			type: 'string',
+			default: 'http://localhost:32400',
+			placeholder: 'http://localhost:32400',
+			description: 'The URL of your Plex Media Server',
+			required: true,
+		},
+		{
+			displayName: 'X-Plex-Token',
+			name: 'plexToken',
+			type: 'string',
+			typeOptions: {
+				password: true,
+			},
+			default: '',
+			description: 'Your Plex authentication token. Find it in Plex settings or browser developer tools.',
+			required: true,
+		},
+		{
+			displayName: 'X-Plex-Client-Identifier',
+			name: 'clientIdentifier',
+			type: 'string',
+			default: 'n8n-plex-node',
+			description: 'A unique identifier for this client',
+			required: true,
+		},
+		{
+			displayName: 'X-Plex-Product',
+			name: 'product',
+			type: 'string',
+			default: 'n8n',
+			description: 'The name of your application',
+		},
+		{
+			displayName: 'X-Plex-Version',
+			name: 'version',
+			type: 'string',
+			default: '1.0.0',
+			description: 'The version of your application',
+		},
+		{
+			displayName: 'X-Plex-Platform',
+			name: 'platform',
+			type: 'string',
+			default: 'Node.js',
+			description: 'The platform running your application',
+		},
+	];
+
+	authenticate: IAuthenticateGeneric = {
+		type: 'generic',
+		properties: {
+			headers: {
+				'X-Plex-Token': '={{$credentials.plexToken}}',
+				'X-Plex-Client-Identifier': '={{$credentials.clientIdentifier}}',
+				'X-Plex-Product': '={{$credentials.product}}',
+				'X-Plex-Version': '={{$credentials.version}}',
+				'X-Plex-Platform': '={{$credentials.platform}}',
+				Accept: 'application/json',
+			},
+		},
+	};
+
+	test: ICredentialTestRequest = {
+		request: {
+			baseURL: '={{$credentials.serverUrl}}',
+			url: '/identity',
+			method: 'GET',
+		},
+	};
+}