feat: setup goose and database module

internal/database/migrations/004_add_notifications.sql

@@ -0,0 +1,10 @@
+-- Note: watch_list_entry columns now in 001_init.sql
+
+-- Add notification preferences
+CREATE TABLE IF NOT EXISTS notification_preference (
+    id TEXT PRIMARY KEY,
+    user_id TEXT NOT NULL REFERENCES user(id) ON DELETE CASCADE,
+    notify_new_episodes BOOLEAN NOT NULL DEFAULT TRUE,
+    created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    UNIQUE(user_id)
+);