add user login sessions

sqlite/schema.sql

@@ -55,3 +55,11 @@ CREATE TABLE IF NOT EXISTS svg_icon (
     id INTEGER PRIMARY KEY AUTOINCREMENT
     ,svg TEXT NOT NULL
 );
+
+
+CREATE TABLE IF NOT EXISTS user_sessions (
+    id TEXT PRIMARY KEY
+    ,user_id TEXT NOT NULL UNIQUE
+    ,created_at TEXT NOT NULL
+    ,FOREIGN KEY (user_id) REFERENCES user(id)
+);