feat: Add GitHub Actions CI and professional README

db/init.sql

@@ -0,0 +1,8 @@
+CREATE TABLE IF NOT EXISTS greetings (
+    id SERIAL PRIMARY KEY,
+    greeting_text TEXT NOT NULL DEFAULT 'Привет! Добро пожаловать!'
+);
+
+INSERT INTO greetings (greeting_text)
+SELECT 'Привет! Добро пожаловать!'
+WHERE NOT EXISTS (SELECT 1 FROM greetings WHERE id = 1);