fix: chunk byline IN clauses to stay within D1 SQL variable limit

[baezor]

What does this PR do?

Fixes unbounded IN (?, ?, …) clauses in byline hydration that exceed Cloudflare D1's SQL bound-parameter limit when querying large collections.

Adds a chunks() utility (utils/chunks.ts) and applies it defense-in-depth at the repository level so any caller is protected:

• BylineRepository.getContentBylinesMany — deduplicates IDs, then chunks content_id IN (…)
• BylineRepository.findByUserIds — chunks user_id IN (…)
• getAuthorIds (bylines/index.ts) — chunks id IN (…) raw SQL

Each batch is capped at 50 IDs, well within D1's limit. Content IDs are also deduplicated before chunking to prevent duplicate credits when the same ID spans multiple chunks.

Closes #219

Type of change

• Bug fix
• Feature (requires approved Discussion)
• Refactor (no behavior change)
• Documentation
• Performance improvement
• Tests
• Chore (dependencies, CI, tooling)

Checklist

• I have read CONTRIBUTING.md
• pnpm typecheck passes
• pnpm --silent lint:json | jq '.diagnostics | length' returns 0
• pnpm test passes (or targeted tests for my change)
• pnpm format has been run
• I have added/updated tests for my changes (if applicable)
• I have added a changeset (if this PR changes a published package)
• New features link to an approved Discussion: https://github.com/emdash-cms/emdash/discussions/...

AI-generated code disclosure

• This PR includes AI-generated code

Screenshots / test output

All 26 tests pass across 3 test files (10 new):

 ✓ chunks > returns empty array for empty input
 ✓ chunks > returns single chunk when array fits within size
 ✓ chunks > splits array into even chunks
 ✓ chunks > handles remainder in last chunk
 ✓ chunks > handles chunk size of 1
 ✓ chunks > handles array exactly equal to chunk size
 ✓ SQL_BATCH_SIZE > is 50
 ✓ BylineRepository > getContentBylinesMany handles more IDs than SQL_BATCH_SIZE
 ✓ BylineRepository > getContentBylinesMany does not duplicate credits for repeated content IDs
 ✓ BylineRepository > findByUserIds handles more IDs than SQL_BATCH_SIZE
 ✓ getBylinesForEntries > handles batches larger than SQL_BATCH_SIZE across explicit and inferred bylines

[changeset-bot]

🦋 Changeset detected

Latest commit: fddf1ee

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 9 packages

Name	Type
emdash	Patch
@emdash-cms/cloudflare	Patch
@emdash-cms/plugin-ai-moderation	Patch
@emdash-cms/plugin-atproto	Patch
@emdash-cms/plugin-audit-log	Patch
@emdash-cms/plugin-color	Patch
@emdash-cms/plugin-embeds	Patch
@emdash-cms/plugin-forms	Patch
@emdash-cms/plugin-webhook-notifier	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions]

All contributors have signed the CLA ✍️ ✅
_{Posted by the CLA Assistant Lite bot.}

[baezor]

I have read the CLA Document and I hereby sign the CLA