Fix WASM bundler compatibility

[lodyai]

Summary

• add a browser package remap for Loro WASM glue so browser bundlers avoid the bundler .wasm static import path
• add a synchronous browser glue target and include browser artifacts in the published packages
• make the base64 entry friendlier to esbuild, Rollup, and Next Webpack by removing browser-visible Node builtin requires and top-level await
• add bundler smoke tests covering Vite 5/6/7/8, rolldown-vite, Webpack 5, Rsbuild 2, Rspack 2, Parcel 2, esbuild, Rollup, and Next 16 Turbopack/Webpack

Fixes #975

Validation

• node --check examples/bundler-smoke-tests/scripts/run.mjs
• node --check crates/loro-wasm/scripts/browser_patch.js
• pnpm dlx deno check --no-lock crates/loro-wasm/scripts/post-rollup.ts
• pnpm --dir examples/bundler-smoke-tests run list
• LORO_SMOKE_PACKAGE=loro-crdt@1.12.1 pnpm --dir examples/bundler-smoke-tests run test rolldown-vite (confirmed old package fails)
• LORO_SMOKE_PACKAGE=file:/tmp/loro-975-smoke-pkg/loro-crdt-patched pnpm --dir examples/bundler-smoke-tests run test rolldown-vite
• LORO_SMOKE_PACKAGE=loro-crdt@1.12.1 pnpm --dir examples/bundler-smoke-tests run test esbuild-base64 (confirmed old package fails)
• LORO_SMOKE_PACKAGE=file:/tmp/loro-975-smoke-pkg/loro-crdt-patched pnpm --dir examples/bundler-smoke-tests run test esbuild-base64 rollup-base64 esbuild-default-copy rollup-default-copy
• LORO_SMOKE_PACKAGE=file:/tmp/loro-975-smoke-pkg/loro-crdt-patched pnpm --dir examples/bundler-smoke-tests run test next16-webpack
• git diff --check

[github-actions]

WASM Size Report

• Original size: 3092.65 KB
• Gzipped size: 991.97 KB
• Brotli size: 690.99 KB