build: Configure Vite for library build and finalize package fields

- Add `vite-plugin-dts` dev dependency.
- Create `vite.config.ts` specifically for library build mode:
    - Configure ESM and UMD outputs (`dist/digiid-ts.es.js`, `dist/digiid-ts.umd.js`).
    - Set up `vite-plugin-dts` for generating `dist/index.d.ts`.
    - Externalize Node.js built-ins and 'digibyte-message' dependency.
- Update `package.json`:
    - Change `scripts.build` to `vite build`.
    - Point `main`, `module`, and `types` fields to the correct files in `dist/`.
- Run and verify the build process successfully generates the expected distribution files.

1 files changed, 4 insertions, 3 deletions

diff --git a/package.json b/package.json
index 895c8b2..990ea54 100644
--- a/package.json
+++ b/package.json
@@ -2,15 +2,15 @@
   "name": "digiid-ts",
   "version": "0.1.0",
   "description": "A modern TypeScript implementation of the DigiID authentication protocol.",
-  "main": "dist/index.js",
-  "module": "dist/index.mjs",
+  "main": "dist/digiid-ts.umd.js",
+  "module": "dist/digiid-ts.es.js",
   "types": "dist/index.d.ts",
   "type": "module",
   "files": [
     "dist"
   ],
   "scripts": {
-    "build": "tsc && vite build",
+    "build": "vite build",
     "dev": "vite",
     "test": "vitest run",
     "test:watch": "vitest",
@@ -55,6 +55,7 @@
     "ts-node": "^10.9.2",
     "typescript": "^5.8.3",
     "vite": "^6.2.5",
+    "vite-plugin-dts": "^4.5.3",
     "vitest": "^3.1.1"
   },
   "dependencies": {