Update build configuration and package dependencies. Changed build script to use tsup for generating both ESM and CJS outputs. Updated package.json to reflect new main and module entries. Added .gitignore entries for .cjs and .d.cts files. Removed tsconfig.build.json as it's no longer needed.

Author: serslon

.gitignore

@@ -1,5 +1,7 @@
 node_modules/
 dist/
+*.cjs
+*.d.cts
 coverage/
 .env
 .env.*

README.md

@@ -14,6 +14,18 @@ Type-safe Node.js client for the [Astrology API v3.0.0](https://api.astrology-ap
 npm install @procoders/astrology-api-client
 ```
 
+### Usage
+
+#### ES Modules
+```ts
+import { AstrologyClient } from '@procoders/astrology-api-client';
+```
+
+#### CommonJS
+```js
+const { AstrologyClient } = require('@procoders/astrology-api-client');
+```
+
 ### Environment Variables
 | Variable | Required | Description |
 | --- | --- | --- |
@@ -113,7 +125,7 @@ Pass `debug: true` and optionally supply a custom `logger` function. Setting `AS
 npm run lint            # ESLint with @typescript-eslint + Prettier
 npm run test            # Vitest watch mode
 npm run test:coverage   # Vitest with V8 coverage (enforced at 100 %)
-npm run build           # TypeScript build (emits ESM to dist/)
+npm run build           # tsup build emitting ESM (.js) + CJS (.cjs)
 ```
 
 ### Project Structure