feat: add simple jwt middleware and update oauth handlers

backend/internal/storage/migrations.go

@@ -6,5 +6,13 @@ CREATE TABLE IF NOT EXISTS posts(
 	title TEXT NOT NULL,
 	content TEXT NOT NULL,
 	CREATED_AT DATETIME DEFAULT CURRENT_TIMESTAMP
-	);
+);
+
+CREATE TABLE IF NOT EXISTS users(
+	id INTEGER PRIMARY KEY AUTOINCREMENT,
+	email TEXT,
+	github_id TEXT,
+	github_login TEXT,
+	avatar_url TEXT
+);
 `