Block Directory: Make downloadable block item labels translatable.

[jorgefilipecosta]

Fixes the four downloadable block item labels in the Block Directory that could not be translated.

The getDownloadableBlockLabel helper in downloadable-block-list-item passes its format strings straight to sprintf without wrapping them in __(). The translator comments are in place, but because the strings never go through an i18n function they are not extracted for translation and always render in English. These are the "Install %s.", "Add %s.", "Installing %s." and "Retry installing %s." labels used for the tooltip and the accessible label of each result in the inserter's Block Directory search.

To fix this we wrap the four format strings in __(), matching the _n() call already used for the rated variant in the same function. A sweep of the repository did not turn up this pattern anywhere else — the remaining unwrapped sprintf calls are developer-facing error messages, HTML id attributes, or code samples, which should not be translated.

Testing Instructions

1. Run npm run test:unit -- packages/block-directory and verify the tests pass.
2. In the post editor, open the inserter and search for a block that is not installed, so Block Directory results appear.
3. Hover a result and verify its tooltip and accessible label still read "Install . …" as before.
4. Verify the four strings in packages/block-directory/src/components/downloadable-block-list-item/index.js are wrapped in __() with their translator comments, so they get extracted for translation.

AI usage disclosure: fix and description drafted with AI assistance and reviewed by me.

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

If you're merging code through a pull request on GitHub, copy and paste the following into the bottom of the merge commit message.

Co-authored-by: jorgefilipecosta <jorgefilipecosta@git.wordpress.org>
Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

[github-actions]

Size Change: -9 B (0%)

Total Size: 7.81 MB

📦 View Changed

Filename	Size	Change
build/scripts/block-directory/index.min.js	44.1 kB	-9 B (-0.02%)

_{compressed-size-action}

[Mamaduka]

Good catch, @jorgefilipecosta!

It's odd that these went unnoticed for so long.