add db connection, refactor code, add db migration files

db/migrations/000004_create_worlds.up.sql

@@ -0,0 +1,23 @@
+CREATE TABLE IF NOT EXISTS worlds (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    text_id VARCHAR(256) NOT NULL,
+    title VARCHAR(256) NOT NULL,
+    description TEXT NOT NULL,
+    system VARCHAR(256) NOT NULL, 
+    core_version VARCHAR(256) NOT NULL, 
+    system_version VARCHAR(256) NOT NULL,
+    playtime INTEGER NOT NULL,
+    next_session DATETIME NOT NULL,
+
+    created_at DATETIME NOT NULL DEFAULT current_timestamp
+);
+
+CREATE TABLE IF NOT EXISTS worlds_compatibility (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    world_id INTEGER UNIQUE,
+    minimum VARCHAR(64) NOT NULL,
+    verified VARCHAR(64) NOT NULL,
+    maximum VARCHAR(64) NOT NULL,
+
+    FOREIGN KEY (world_id) REFERENCES worlds(id) ON DELETE CASCADE
+);