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>

bot.py

@@ -43,6 +43,7 @@ from nio.crypto.attachments import decrypt_attachment
 from livekit import api, rtc
 from voice import VoiceSession
 from article_summary import ArticleSummaryHandler
+from cron import CronScheduler
 
 BOT_DEVICE_ID = "AIBOT"
 CALL_MEMBER_TYPE = "org.matrix.msc3401.call.member"
@@ -1172,6 +1173,16 @@ class Bot:
             )
         else:
             self.article_handler = None
+        # Cron job scheduler (syncs with matrixhost portal)
+        if PORTAL_URL and BOT_API_KEY:
+            self.cron_scheduler = CronScheduler(
+                portal_url=PORTAL_URL,
+                api_key=BOT_API_KEY,
+                matrix_client=self.client,
+                send_text_fn=self._send_text,
+            )
+        else:
+            self.cron_scheduler = None
 
     async def _has_documents(self, matrix_user_id: str) -> bool:
         """Check if user has documents via local RAG or MatrixHost portal API.
@@ -1259,6 +1270,11 @@ class Bot:
         # Start reminder scheduler
         asyncio.create_task(self._reminder_scheduler())
 
+        # Start cron job scheduler
+        if self.cron_scheduler:
+            asyncio.create_task(self.cron_scheduler.start())
+            logger.info("Cron scheduler task created")
+
         await self.client.sync_forever(timeout=30000, full_state=True)
 
     async def _ensure_cross_signing(self):
@@ -3508,6 +3524,8 @@ class Bot:
                     await self.client.to_device(mac)
 
     async def cleanup(self):
+        if self.cron_scheduler:
+            await self.cron_scheduler.stop()
         await self.client.close()
         if self.lkapi:
             await self.lkapi.aclose()