[Webtoon study] Add original practical test harness for sample-derived webtoon patterns

[realproject7]

Context

After implementing the webtoon study changes, we need an end-to-end test that proves OWS can make an original webtoon episode using the abstract patterns without copying the study samples.

Required Changes

Create a practical test harness for original cartoon stories:

• Generate one short original modern-fantasy episode.
• Generate one short original thriller episode.
• Generate one short original romance episode.
• Generate one short original slice-of-life episode.
• Each test story must include:
  • beat metadata
  • at least one transition/interstitial element
  • at least three semantic bubble kinds
  • at least one text-only or UI/object insert
  • genre-appropriate ending turn
  • QA checklist run
  • preview/edit/export verification

Constraints

• Do not use sample screenshots, copied dialogue, copied character designs, or distinctive plots.
• Test fixtures should be simple and original.
• The harness should run without paid external image generation where possible; use placeholder/generated simple assets or existing test asset pipeline.

Acceptance Criteria

• A documented command or script can create/check the original test stories.
• The harness verifies data model, preview, focused editor state, export order, and QA warnings.
• The harness is usable before npm publish as a smoke test for cartoon changes.

Verification

• Add automated tests where practical.
• Add a manual QA checklist for browser verification.
• Run the harness before the release that ships the webtoon grammar update.