Regenerate image derivatives that img.mjs had been skipping

[enf0rc3]

Split out of #3313, where these files were surfaced. They fix a pre-existing gap in the asset pipeline and stand on their own.

The trap

img.mjs only processes a source image when it has no metadata sidecar:

// Only processes images where there is no json metadata file
if (!fs.existsSync(metaPath)) {
  filesToProcess.push(info);
}

Once a sidecar exists without its derivatives, nothing regenerates them. Three images were stuck that way.

What was stuck

releases/timeline/environment-timeline.png and -button.png were renamed from timeline.png. The sidecar travelled with the source, so img.mjs skipped both, the derivatives kept the old name, and the sidecar kept the old image's dimensions — 1000×535 recorded against an image that is actually 1644×1081. Any consumer trusting those numbers was laying out the wrong box.

api-and-integration/github/github-connections-authorize-app.png had a sidecar and no derivatives at any size. That's the state you get when img.mjs exits mid-write: its toFile() calls at lines 105, 111, 116, 147 and 152 are never awaited, while the sidecar write at line 130 is.

What this does

Deletes the three stale sidecars so img.mjs reprocesses them, and commits the 12 derivative files it produced plus the three corrected sidecars.

The old timeline-*.webp derivatives are unreferenced now, but I left them rather than widening this into a cleanup.

Not fixed here

• The unawaited toFile() calls. img.mjs carries a header saying it comes from Astro Accelerator and local edits get overwritten, so the race wants its own decision.
• .jpeg sources. img.mjs writes .jpg derivatives while getDestination builds the fallback URL from the original extension, so /docs/i/x/…jpeg never exists for the three projects/dashboard images. Replace the magnify-and-new-tab figure with an inline lightbox #3313 handles this by falling back to the original file.

Verifying

Nothing references these paths on main today — getImageInfo runs for :img{} directives only, and none of these images use one. So main stays green either way; this makes the assets correct for anything that starts requesting them.

🤖 Generated with Claude Code

[borland]

This PR is redundant when my cleanup PR merges. There's no value in regenerating the image derivatives in the meantime because nothing references them

[team-marketing-branch-protections]

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[enf0rc3]

Not required as #3281 fixes the need and we will use the new approach