feat(MAT-174): Add cron job scheduler and executors

Cron package that syncs jobs from matrixhost portal API, schedules execution
with timezone-aware timing, and posts results to Matrix rooms. Includes
Brave Search, reminder, and browser scrape (placeholder) executors with
formatter. 31 pytest tests.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/test_cron_executor.py

@@ -0,0 +1,48 @@
+"""Tests for the cron executor dispatch."""
+
+from unittest.mock import AsyncMock
+
+import pytest
+
+from cron.executor import execute_job
+
+
+class TestExecuteJob:
+    @pytest.mark.asyncio
+    async def test_unknown_job_type_returns_error(self):
+        job = {"jobType": "nonexistent", "config": {}}
+        result = await execute_job(
+            job=job, send_text=AsyncMock(), matrix_client=None
+        )
+        assert result["status"] == "error"
+        assert "Unknown job type" in result["error"]
+
+    @pytest.mark.asyncio
+    async def test_dispatches_to_reminder(self):
+        job = {
+            "id": "j1",
+            "name": "Test Reminder",
+            "jobType": "reminder",
+            "config": {"message": "Don't forget!"},
+            "targetRoom": "!room:test",
+        }
+        send_text = AsyncMock()
+        result = await execute_job(job=job, send_text=send_text, matrix_client=None)
+        assert result["status"] == "success"
+        send_text.assert_called_once()
+        assert "Don't forget!" in send_text.call_args[0][1]
+
+    @pytest.mark.asyncio
+    async def test_dispatches_to_browser_scrape_no_profile(self):
+        job = {
+            "id": "j1",
+            "name": "Scrape Test",
+            "jobType": "browser_scrape",
+            "config": {"url": "https://example.com"},
+            "targetRoom": "!room:test",
+            "browserProfile": None,
+        }
+        send_text = AsyncMock()
+        result = await execute_job(job=job, send_text=send_text, matrix_client=None)
+        assert result["status"] == "error"
+        assert "browser profile" in result["error"].lower()