feat(Q5): package event queries and tracker state machine

Add insert/get/update queries for package_events table, and
notification content for PACKAGE_DELIVERED and PACKAGE_REMINDER events.

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

tests/unit/test_package_queries.py

@@ -0,0 +1,21 @@
+import time
+import pytest
+from vigilar.storage.queries import insert_package_event, get_active_packages, update_package_status
+
+def test_insert_package_event(test_db):
+    pkg_id = insert_package_event(test_db, camera_id="front", detected_at=time.time(), status="PRESENT")
+    assert pkg_id > 0
+
+def test_get_active_packages(test_db):
+    now = time.time()
+    insert_package_event(test_db, camera_id="front", detected_at=now, status="PRESENT")
+    insert_package_event(test_db, camera_id="back", detected_at=now, status="COLLECTED")
+    active = get_active_packages(test_db)
+    assert len(active) == 1
+    assert active[0]["camera_id"] == "front"
+
+def test_update_package_status(test_db):
+    pkg_id = insert_package_event(test_db, camera_id="front", detected_at=time.time(), status="PRESENT")
+    update_package_status(test_db, pkg_id, "REMINDED", reminded_at=time.time())
+    active = get_active_packages(test_db)
+    assert active[0]["status"] == "REMINDED"