feat: added data model and ui for main window

deps/tables.ddl

@@ -0,0 +1,15 @@
+CREATE TABLE IF NOT EXISTS clients (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    city TEXT NOT NULL,
+    email TEXT NOT NULL,
+    firstName TEXT NOT NULL,
+    hardwareHash TEXT NOT NULL,
+    lastName TEXT NOT NULL,
+    patronymic TEXT NOT NULL,
+    phone TEXT NOT NULL,
+    yourCompany TEXT NOT NULL,
+    comment TEXT
+);
+
+COMMENT ON TABLE clients IS '';
+COMMENT ON FIELD clients.id IS '';