feat: enable coverage collection

.gitignore

@@ -1,4 +1,5 @@
 node_modules/
 dist/
+coverage/
 
 .DS_Store

jest.config.ts

@@ -1,4 +1,8 @@
 module.exports = {
   preset: "ts-jest",
   testEnvironment: "node",
+  collectCoverage: true,
+  collectCoverageFrom: [
+    "src/**/*.{ts,tsx}",
+  ]
 };