Keep translators comments in the built bundles

The make-pot run on develop reported 27 strings with placeholders and no
`translators:` comment, and every one of them is in build/*.bundle.js - none
in PHP. Adding those comments to src/ would have had no effect: Terser's
default `format.comments` keeps only license banners, so the comments were
being stripped before `wp i18n make-pot` ever saw the bundle. The result
would have been 27 comments written, a rebuild, and no change to either the
warnings or the POT.

Verified with a real webpack run using this repo's exact terserOptions:

  current config                          comment stripped, LICENSE.txt emitted
  + format.comments = /translators:/i     comment kept,     LICENSE.txt emitted
  + extractComments: false as well        comment kept,     LICENSE.txt dropped

So only the format.comments line is added. @wordpress/scripts also sets
extractComments: false in its own config, but copying that here would stop
the 8 *.bundle.js.LICENSE.txt files being emitted for no benefit - preserving
a comment and extracting one are separate things.

Confirmed end to end that make-pot then picks it up from minified output,
which is the part that was not obvious: Terser keeps the comment on its own
line ahead of the statement, and make-pot associates it correctly.

  #. translators: 1: current issue number, 2: total issues
  #: build/b.bundle.js:4
  #, js-format
  msgid "Issue %1$d of %2$d"

The warning disappears for that string, and both the `#.` comment and the
`#,` flag are kept by make-pot.yml's diff filter, so documenting these
strings will correctly be detected as a POT change and raise the update PR.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019LoLgW7oFjBPxGea9kiZJ2

Author: pattonwebz

webpack.config.js

@@ -69,6 +69,16 @@ module.exports = {
 						reserved: [ '__', '_n', '_x', '_nx' ], // Prevent webpack from using these translation function names and mangling them in the source.
 					},
 					keep_fnames: /(__|_n|_x|_nx)$/,
+					format: {
+						// Keep `translators:` comments in the built bundles. Terser's
+						// default drops every comment except license banners, and
+						// `wp i18n make-pot` scans build/*.bundle.js rather than src/,
+						// so without this a translators comment written in src/ never
+						// reaches the POT and the string stays undocumented.
+						// This only preserves the comment, it does not extract it, so
+						// the existing *.LICENSE.txt output is unaffected.
+						comments: /translators:/i,
+					},
 				},
 			} ),
 			new CssMinimizerPlugin(),