fix: update test fixtures for SQLite storage migration

All store tests were passing file paths instead of Database objects
after the JSON-to-SQLite migration. Updated fixtures to create temp
Database instances, rewrote backup e2e tests for binary .db format,
and fixed config tests for the simplified StorageConfig.

server/tests/e2e/test_backup_flow.py

@@ -1,11 +1,9 @@
 """E2E: Backup and restore flow.
 
-Tests creating entities, backing up, deleting, then restoring from backup.
+Tests creating entities, backing up (SQLite .db file), deleting, then restoring.
 """
 
 import io
-import json
-
 
 
 class TestBackupRestoreFlow:
@@ -42,20 +40,12 @@ class TestBackupRestoreFlow:
         resp = client.get("/api/v1/color-strip-sources")
         assert resp.json()["count"] == 1
 
-        # 2. Create a backup (GET returns a JSON file)
+        # 2. Create a backup (GET returns a SQLite .db file)
         resp = client.get("/api/v1/system/backup")
         assert resp.status_code == 200
-        backup_data = resp.json()
-        assert backup_data["meta"]["format"] == "ledgrab-backup"
-        assert "stores" in backup_data
-        assert "devices" in backup_data["stores"]
-        assert "color_strip_sources" in backup_data["stores"]
-
-        # Verify device is in the backup.
-        # Store files have structure: {"version": "...", "devices": {id: {...}}}
-        devices_store = backup_data["stores"]["devices"]
-        assert "devices" in devices_store
-        assert len(devices_store["devices"]) == 1
+        backup_bytes = resp.content
+        # SQLite files start with this magic header
+        assert backup_bytes[:16].startswith(b"SQLite format 3")
 
         # 3. Delete all created entities
         resp = client.delete(f"/api/v1/color-strip-sources/{css_id}")
@@ -69,52 +59,37 @@ class TestBackupRestoreFlow:
         resp = client.get("/api/v1/color-strip-sources")
         assert resp.json()["count"] == 0
 
-        # 4. Restore from backup (POST with the backup JSON as a file upload)
-        backup_bytes = json.dumps(backup_data).encode("utf-8")
+        # 4. Restore from backup (POST with the .db file upload)
         resp = client.post(
             "/api/v1/system/restore",
-            files={"file": ("backup.json", io.BytesIO(backup_bytes), "application/json")},
+            files={"file": ("backup.db", io.BytesIO(backup_bytes), "application/octet-stream")},
         )
         assert resp.status_code == 200, f"Restore failed: {resp.text}"
         restore_result = resp.json()
         assert restore_result["status"] == "restored"
-        assert restore_result["stores_written"] > 0
-
-        # 5. After restore, stores are written to disk but the in-memory
-        # stores haven't been re-loaded (normally a server restart does that).
-        # Verify the backup file was written correctly by reading it back.
-        # The restore endpoint writes JSON files; we check the response confirms success.
         assert restore_result["restart_scheduled"] is True
 
-    def test_backup_contains_all_store_keys(self, client):
-        """Backup response includes entries for all known store types."""
+    def test_backup_is_valid_sqlite(self, client):
+        """Backup response is a valid SQLite database file."""
         resp = client.get("/api/v1/system/backup")
         assert resp.status_code == 200
-        stores = resp.json()["stores"]
-        # At minimum, these critical stores should be present
-        expected_keys = {
-            "devices", "output_targets", "color_strip_sources",
-            "capture_templates", "value_sources",
-        }
-        assert expected_keys.issubset(set(stores.keys()))
+        assert resp.content[:16].startswith(b"SQLite format 3")
+        # Should have Content-Disposition header for download
+        assert "attachment" in resp.headers.get("content-disposition", "")
 
     def test_restore_rejects_invalid_format(self, client):
-        """Uploading a non-backup JSON file should fail validation."""
-        bad_data = json.dumps({"not": "a backup"}).encode("utf-8")
+        """Uploading a non-SQLite file should fail validation."""
+        bad_data = b"not a database file at all, just random text content"
         resp = client.post(
             "/api/v1/system/restore",
-            files={"file": ("bad.json", io.BytesIO(bad_data), "application/json")},
+            files={"file": ("bad.db", io.BytesIO(bad_data), "application/octet-stream")},
         )
         assert resp.status_code == 400
 
-    def test_restore_rejects_empty_stores(self, client):
-        """A backup with no recognized stores should fail."""
-        bad_backup = {
-            "meta": {"format": "ledgrab-backup", "format_version": 1},
-            "stores": {"unknown_store": {}},
-        }
+    def test_restore_rejects_empty_file(self, client):
+        """A tiny file should fail validation."""
         resp = client.post(
             "/api/v1/system/restore",
-            files={"file": ("bad.json", io.BytesIO(json.dumps(bad_backup).encode()), "application/json")},
+            files={"file": ("tiny.db", io.BytesIO(b"x" * 50), "application/octet-stream")},
         )
         assert resp.status_code == 400