Merge main into v2/main so main-source.yml shares history and the v2.0.0 merge is clean #5171

The v2.0.0 merge PR (#5166) stopped being a pure merge after #5169. git merge-tree --write-tree origin/main origin/v2/main reports an add/add conflict in .github/workflows/main-source.yml:

• The last commit main and v2/main share is the v1.0.0 merge (89701afa). It has no main-source.yml.
• f39bc6bb (ci: bring the main-source guard to main (bootstrap for #5119) #5122) added the file to main directly. v2/main added its own copy.
• With no shared version of the file, git can only merge the two copies while they are byte-identical. fix: raise the TypeScript servers' Node floor to 24 #5169 changed v2/main's copy to node-version: 24.

Change

Merge origin/main into v2/main so the two branches share the file's history:

1. Resolve the conflict to main's copy (node-version: 22).
2. Re-apply fix: raise the TypeScript servers' Node floor to 24 #5169's node-version: 24 in a separate commit.

After that, v2/main contains every commit on main. The merge into main then produces v2/main's tree, and #5166 can be fast-forwarded to it.

The PR must be merged with "Create a merge commit". A squash or rebase would drop the shared history and bring the conflict back.