feat(pipeline): allow overriding the notes package name per run

[cmglezpdev]

What this changes

runExtraction accepts an optional packageName?: (dirName: string) => string callback that overrides the notes folder baked into prompt.md, without touching the on-disk package directory.

Why

Playlist members need their notes folder nested as <playlist-slug>/NN-<video-slug> while remaining ordinary standalone packages. The callback form is needed because the video slug only exists after metadata resolution. This is the only change the whole chain makes to run-extraction.ts.

How to verify

pnpm typecheck
pnpm vitest run src/pipeline/run-extraction.test.ts --exclude '**/.claude/**'

Checklist

• pnpm typecheck and pnpm test pass
• Commits follow Conventional Commits

Scope

• Includes: the option + one test.
• Excludes: everything else.

Chain Context

Field	Value
Chain	playlist-support
Tracker PR	#40
Position	3 of 6
Base	feat/playlist-support-02-store
Depends on	PR 2 (#42)
Follow-up	PR 4 (playlist prompt)
Review budget	25 / 400

Chain Overview

main
 └── #40 tracker: feat/playlist-support
      └── #41 listing → #42 store → 03a packageName → 03b prompt → 04 orchestrator → 05 CLI
          (this PR: 📍 3)