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>

composer.json

@@ -0,0 +1,34 @@
+{
+	"name": "pniebeling/workflow_deck_automation",
+	"description": "Automates moving overdue Deck cards between stacks, configurable per user, via Deck's own internal classes.",
+	"license": "AGPL-3.0-or-later",
+	"type": "project",
+	"config": {
+		"optimize-autoloader": true,
+		"sort-packages": true,
+		"platform": {
+			"php": "8.2"
+		}
+	},
+	"autoload": {
+		"psr-4": {
+			"OCA\\WorkflowDeckAutomation\\": "lib/"
+		}
+	},
+	"autoload-dev": {
+		"psr-4": {
+			"OCA\\WorkflowDeckAutomation\\Tests\\": "tests/"
+		}
+	},
+	"require-dev": {
+		"nextcloud/ocp": "dev-master",
+		"nextcloud/coding-standard": "^1.3",
+		"phpunit/phpunit": "^10.5"
+	},
+	"scripts": {
+		"lint": "find lib tests -name '*.php' -print0 | xargs -0 -n1 -- php -l",
+		"cs:check": "php-cs-fixer fix --dry-run --diff",
+		"cs:fix": "php-cs-fixer fix",
+		"test:unit": "phpunit --testsuite unit"
+	}
+}