fix(linter/import/no-duplicates): avoid duplicate commas when merging imports

[camc314]

Summary

• skip empty specifier segments created by trailing commas while merging duplicate imports
• prevent a following import declaration from adding a second comma
• add a three-import regression that previously produced invalid a,b,,c syntax

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.

[codspeed-hq]

Merging this PR will not alter performance

✅ 5 untouched benchmarks
⏩ 66 skipped benchmarks¹

---

_{Comparing codex/fix-no-duplicates-extra-comma (4235a96) with main (5b20828)²}

Footnotes

1. 66 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on main (261aa39) during the generation of this report, so 5b20828 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[oxc-guard]

Oxlint Ecosystem CI

suite	result
microsoft/vscode	✅
DefinitelyTyped/DefinitelyTyped	✅
napi-rs/napi-rs	✅
bbc/simorgh	✅
toeverything/affine	✅
elastic/kibana	✅
bluesky-social/social-app	✅
Milkdown/milkdown	✅
calcom/cal.com	✅
rolldown/rolldown	❌
oven-sh/bun	❌
sidebase/nuxt-auth	❌
outline/outline	✅
glide-browser/glide	❌
renovatebot/renovate	❌
date-fns/date-fns	❌
monkeytypegame/monkeytype	✅
preactjs/preact	❌
nestjs/nest	✅
cloudflare/agents	✅
vercel/turborepo	❌
PostHog/posthog	✅
cloudflare/workers-sdk	❌
formatjs/formatjs	✅
npmx-dev/npmx.dev	✅
vercel/next.js	✅
matter-js/matter.js	✅
oxidecomputer/console	✅
actualbudget/actual	❌

[camc314]

Merge activity

• Jul 13, 3:05 PM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
• Jul 13, 3:05 PM UTC: camc314 added this pull request to the Graphite merge queue.
• Jul 13, 3:14 PM UTC: Merged by the Graphite merge queue.