fetchFallbackArtifactShots doesn't paginate the artifacts-list read, unlike its sibling reads in the same visual-capture subsystem

[JSONbored]

Context

src/review/visual/actions-fallback.ts's fetchFallbackArtifactShots (line 378) fetches only GET /repos/{o}/{r}/actions/runs/{runId}/artifacts?per_page=100 (page 1) and does .find() for FALLBACK_ARTIFACT_NAME.

Its sibling module src/review/visual/preview-url.ts explicitly documents this exact failure mode ("a single per_page=100 read silently truncates... indistinguishable from an empty one") and was hardened with a bounded pagination walker across four separate endpoints (#7779, #7805, #7469). fetchFallbackArtifactShots — added later, in the same visual-capture epic (#4112) — never got the same treatment.

If the dispatched fallback workflow ever attaches more than 100 artifacts to one run (extra diagnostic/log artifacts, a future workflow change), the target artifact silently falls off page 1 and the function returns [] exactly as if no artifact existed.

⚠️ Required pattern — read preview-url.ts's bounded pagination walker (the fix from #7779/#7805/#7469) before starting. Reuse the same pagination approach for fetchFallbackArtifactShots's artifacts-list read — do not invent a second pagination mechanism.

Requirements

• fetchFallbackArtifactShots must page through the full artifacts list (bounded, mirroring preview-url.ts's existing walker) instead of reading only page 1.
• No behavior change when a run has ≤100 artifacts.

Deliverables

• fetchFallbackArtifactShots finds the target artifact regardless of how many artifacts are attached to the run (within the same bound preview-url.ts uses).
• Existing single-page behavior unchanged for runs with ≤100 artifacts.

Test Coverage Requirements

src/** — 99%+ Codecov patch target, both branches. Add a test with a mocked multi-page artifacts response (target artifact on page 2+) asserting it's still found, plus the existing single-page case continuing to pass.

Expected Outcome

The visual-capture fallback path finds its target artifact regardless of how many artifacts a run has attached, matching the hardening preview-url.ts already has.

Links & Resources

• src/review/visual/actions-fallback.ts (line 378, fetchFallbackArtifactShots)
• src/review/visual/preview-url.ts (the pagination walker to reuse, findPreviewUrlFromChecks doesn't paginate check-runs, unlike its sibling functions in the same file #7779/getLatestDeploymentStatus doesn't paginate deployments/statuses reads, unlike its siblings in the same file #7805/fix(review): paginate preview-url.ts's PR-comment and check-run GitHub reads #7469)
• feat(review): GitHub-Actions build-and-serve fallback for repos with no CI preview deploy #4112 (the shared visual-capture epic both modules belong to)

[linear-code]

JSO-5544