Add DB constraint to prevent empty beamline name

Author: tpoliaw

migrations/0001_init.up.sql

@@ -1,6 +1,6 @@
 CREATE TABLE beamline (
     id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
-    name TEXT UNIQUE NOT NULL,
+    name TEXT UNIQUE NOT NULL CHECK (length(name) > 0),
     -- Default to 0 so scan numbering starts at 1
     scan_number INTEGER NOT NULL DEFAULT 0 CHECK (scan_number >= 0),