docs: deprecate the loader and link the migration example

[alexander-akait]

Summary

webpack shims these modules without a loader: ProvidePlugin binds a name the module only reads, and the add-imports example does the rest — the side-effect require and the wrapper — with the NormalModule.processResult hook, in a plugin that fits in the configuration. This marks the loader deprecated and adds a per-option migration table pointing there. Depends on webpack/webpack#21948, which adds that example.

What kind of change does this PR introduce?

docs — README only, no behavior change.

Did you add tests for your changes?

No; nothing executable changed. prettier and cspell are clean on the file.

Does this PR introduce a breaking change?

No. Whether the loader also starts warning at build time, and when the package gets npm deprecate, is a separate call.

If relevant, what needs to be documented once your changes are merged or what have you already documented?

The webpack.js.org Shimming guide still recommends this loader and should point at the example instead.

Use of AI

Claude Code drafted the notice and the migration table under my direction, and I reviewed it. The table's claims were checked against real builds during the investigation behind webpack/webpack#21948 — including that ProvidePlugin hoists its binding above the module body, so it preserves this loader's ordering.

---

🤖 Generated with Claude Code

https://claude.ai/code/session_01XVjgpHQ9f9sBG3KTdwxAkK

---

Generated by Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.96%. Comparing base (dc67bf0) to head (cdea13e).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #234   +/-   ##
=======================================
  Coverage   91.96%   91.96%           
=======================================
  Files           3        3           
  Lines         224      224           
  Branches       87       87           
=======================================
  Hits          206      206           
  Misses         12       12           
  Partials        6        6           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.