Initial commit: scheduler service extraction from portainer-core

Extracted standalone scheduler service with:
- FastAPI REST API for task management
- APScheduler-based task execution
- PostgreSQL persistence
- Docker container support
- Gitea Actions CI/CD workflow

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/test_example_executor.py

@@ -0,0 +1,80 @@
+"""
+Tests for the example executor.
+"""
+import pytest
+import asyncio
+from src.executors import example_executor
+from src.config import Settings
+
+
+@pytest.mark.executor
+@pytest.mark.unit
+class TestExampleExecutor:
+    """Tests for example_executor module."""
+
+    @pytest.mark.asyncio
+    async def test_executor_returns_success_message(self, test_settings: Settings):
+        """Test that executor returns success message."""
+        config = {
+            "message": "Test message",
+            "delay_seconds": 0
+        }
+
+        result = await example_executor.execute(config, test_settings)
+
+        assert "Test message" in result
+        assert "took" in result.lower()
+
+    @pytest.mark.asyncio
+    async def test_executor_with_delay(self, test_settings: Settings):
+        """Test that executor respects delay_seconds."""
+        import time
+
+        config = {
+            "message": "Delayed test",
+            "delay_seconds": 1
+        }
+
+        start = time.time()
+        result = await example_executor.execute(config, test_settings)
+        elapsed = time.time() - start
+
+        # Should take at least 1 second
+        assert elapsed >= 1.0
+        assert "Delayed test" in result
+
+    @pytest.mark.asyncio
+    async def test_executor_with_zero_delay(self, test_settings: Settings):
+        """Test that executor works with zero delay."""
+        config = {
+            "message": "Instant",
+            "delay_seconds": 0
+        }
+
+        result = await example_executor.execute(config, test_settings)
+
+        assert "Instant" in result
+        assert "took 0s" in result
+
+    @pytest.mark.asyncio
+    async def test_executor_missing_config_fields(self, test_settings: Settings):
+        """Test that executor handles missing config fields gracefully."""
+        config = {}
+
+        # Should use defaults
+        result = await example_executor.execute(config, test_settings)
+
+        assert isinstance(result, str)
+        assert "took" in result.lower()
+
+    @pytest.mark.asyncio
+    async def test_executor_invalid_delay_type(self, test_settings: Settings):
+        """Test that executor handles invalid delay type."""
+        config = {
+            "message": "Test",
+            "delay_seconds": "invalid"  # Should be int
+        }
+
+        # Should raise TypeError or handle gracefully
+        with pytest.raises((TypeError, ValueError)):
+            await example_executor.execute(config, test_settings)