Add Deck workflow automation Nextcloud app

Ports the standalone due-date cron script into a proper Nextcloud 34
app with a personal-settings UI, per-user workflow configuration
(source/target stack, assigned-user and label filters, email
notification), a TimedJob background runner, and Gitea CI pipelines.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

vite.config.js

@@ -0,0 +1,12 @@
+import { createAppConfig } from '@nextcloud/vite-config'
+
+export default createAppConfig({
+	'workflow-deck-automation-personal-settings': 'src/main.js',
+}, {
+	createEmptyCSSEntryPoints: true,
+	config: {
+		build: {
+			cssCodeSplit: true,
+		},
+	},
+})