add db connection, refactor code, add db migration files

db/migrations/000005_create_users.up.sql

@@ -0,0 +1,32 @@
+CREATE TABLE IF NOT EXISTS users (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    name VARCHAR(256) NOT NULL,
+    role INTEGER NOT NULL,
+    character VARCHAR(128) NOT NULL,
+    color VARCHAR(128) NOT NULL,
+    pronouns VARCHAR(128) NOT NULL,
+
+    created_at DATETIME NOT NULL DEFAULT current_timestamp
+);
+
+CREATE TABLE IF NOT EXISTS users_hotbar (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    user_id INTEGER,
+    key TEXT NOT NULL,
+    value TEXT NOT NULL,
+
+    FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
+);
+
+CREATE TABLE IF NOT EXISTS users_stats (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    user_id INTEGER,
+    core_version TEXT NOT NULL,
+    system_id VARCHAR(64) NOT NULL,
+    system_version VARCHAR(64) NOT NULL,
+    created_time INTEGER NOT NULL,
+    modified_time INTEGER NOT NULL,
+    last_modified_by VARCHAR(256) NOT NULL,
+
+    FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
+);