Replace rollup typescript plugin with babel for asyncImportHelper preprocessing

The @rollup/plugin-typescript performs type-checking on all imported files,
which generates hundreds of warnings for the jsPDF codebase. Since we only
need to strip TypeScript type annotations from asyncImportHelper.ts (no actual
type checking is needed), switching to @rollup/plugin-babel with
@babel/preset-typescript provides a cleaner solution.

Changes:
- Replace typescript plugin with babel plugin in both karma configs
- Use @babel/preset-typescript which only strips types (no type checking)
- Verified locally that rollup processing completes with no TypeScript warnings

This eliminates all the type-checking warnings while still correctly transpiling
the asyncImportHelper.ts files to ES modules.

Author: claude

test/deployment/esm/karma.conf.js

@@ -1,7 +1,7 @@
 const karmaConfig = require("../../karma.common.conf.js");
 const resolve = require("rollup-plugin-node-resolve");
 const commonjs = require("rollup-plugin-commonjs");
-const typescript = require("@rollup/plugin-typescript");
+const { babel } = require("@rollup/plugin-babel");
 
 module.exports = config => {
   config.set({
@@ -55,10 +55,10 @@ module.exports = config => {
 
     rollupPreprocessor: {
       plugins: [
-        typescript({
-          tsconfig: false,
-          module: "esnext",
-          target: "es2015"
+        babel({
+          babelHelpers: "bundled",
+          extensions: [".ts", ".js"],
+          presets: ["@babel/preset-typescript"]
         }),
         resolve(),
         commonjs()

test/unit/karma.conf.js

@@ -3,7 +3,7 @@
 const karmaConfig = require("../karma.common.conf.js");
 const resolve = require("rollup-plugin-node-resolve");
 const commonjs = require("rollup-plugin-commonjs");
-const typescript = require("@rollup/plugin-typescript");
+const { babel } = require("@rollup/plugin-babel");
 
 module.exports = config => {
   config.set({
@@ -41,10 +41,10 @@ module.exports = config => {
 
     rollupPreprocessor: {
       plugins: [
-        typescript({
-          tsconfig: false,
-          module: "esnext",
-          target: "es2015"
+        babel({
+          babelHelpers: "bundled",
+          extensions: [".ts", ".js"],
+          presets: ["@babel/preset-typescript"]
         }),
         resolve(),
         commonjs()