feat!: enable asyncWebAssembly by default

[LingyuCoder]

Summary

This PR changes the default value of experiments.asyncWebAssembly from false to true, making async WebAssembly support enabled by default in Rspack. This aligns with the modern WebAssembly ESM integration specification and provides better out-of-the-box support for WebAssembly modules.

Previously, asyncWebAssembly was only enabled by default when experiments.futureDefaults was set to true. With this change, users no longer need to explicitly enable this option to use async WebAssembly modules.

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

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[github-actions]

Rsdoctor Bundle Diff Analysis

Found 5 projects in monorepo, 3 projects with changes.

📊 Quick Summary

Project	Total Size	Change
react-10k	5.7 MB	-8.0 B (-0.0%)
react-1k	825.4 KB	0
react-5k	2.7 MB	+1.0 B (0.0%)
rome	985.8 KB	+1.7 KB (0.2%)
ui-components	2.1 MB	0

📋 Detailed Reports (Click to expand)

📁 react-10k

Path: ../build-tools-performance/cases/react-10k/dist/rsdoctor-data.json

📌 Baseline Commit: fe1e14c1d5 | PR: #12763

Metric	Current	Baseline	Change
📊 Total Size	5.7 MB	5.7 MB	-8.0 B (-0.0%)
📄 JavaScript	5.7 MB	5.7 MB	-8.0 B (-0.0%)
🎨 CSS	21.0 B	21.0 B	0
🌐 HTML	0 B	0 B	0
📁 Other Assets	0 B	0 B	0

📦 Download Diff Report: react-10k Bundle Diff

📁 react-5k

Path: ../build-tools-performance/cases/react-5k/dist/rsdoctor-data.json

📌 Baseline Commit: fe1e14c1d5 | PR: #12763

Metric	Current	Baseline	Change
📊 Total Size	2.7 MB	2.7 MB	+1.0 B (0.0%)
📄 JavaScript	2.7 MB	2.7 MB	+1.0 B (0.0%)
🎨 CSS	21.0 B	21.0 B	0
🌐 HTML	0 B	0 B	0
📁 Other Assets	0 B	0 B	0

📦 Download Diff Report: react-5k Bundle Diff

📁 rome

Path: ../build-tools-performance/cases/rome/dist/rsdoctor-data.json

📌 Baseline Commit: fe1e14c1d5 | PR: #12763

Metric	Current	Baseline	Change
📊 Total Size	985.8 KB	984.2 KB	+1.7 KB (0.2%)
📄 JavaScript	985.8 KB	984.2 KB	+1.7 KB (0.2%)
🎨 CSS	0 B	0 B	0
🌐 HTML	0 B	0 B	0
📁 Other Assets	0 B	0 B	0

📦 Download Diff Report: rome Bundle Diff

Generated by Rsdoctor GitHub Action

[github-actions]

📦 Binary Size-limit

Comparing a8ef55b to chore: limit threads for codspeed benchmark (#12763) by CPunisher

🎉 Size decreased by 322.75KB from 47.99MB to 47.68MB (⬇️0.66%)

[codspeed-hq]

CodSpeed Performance Report

Merging this PR will not alter performance

_{Comparing feat/enable-async-webassembly-by-default (a8ef55b) with v2 (a0a802b)¹}

Summary

✅ 16 untouched benchmarks
⏩ 1 skipped benchmark²

Footnotes

1. No successful run was found on v2 (bec0dda) during the generation of this report, so a0a802b was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

2. 1 benchmark was skipped, so the baseline result was used instead. If it was deleted from the codebase, click here and archive it to remove it from the performance reports. ↩