Write the first 16 concepts (no boxed sections)
Imported from GitHub issue [El-SaMa/tekori#4](https://github.com/El-SaMa/tekori/issues/4) by @El-SaMa.
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## Goal
The concept recipes themselves. Each one written in our own words, mapped to kit components (#6-#10), with a still version for reduced motion and a phone version.
## The set (one file each, format in #3)
- [ ] `continuous-canvas`: one flowing surface, no section borders; content blocks placed on a loose grid that drifts; background colour shifts as you scroll.
- [ ] `horizontal-story`: the middle of the page scrolls sideways (pinned), chapters as panels.
- [ ] `stacked-cards`: sections are cards that stack on top of each other as you scroll.
- [ ] `type-as-layout`: giant display type is the structure; photos tuck behind and between letters.
- [ ] `split-fixed`: one half fixed (photo, 3D object or brand mark), the other half scrolls.
- [ ] `collage-scrapbook`: overlapping photos, notes, stickers; slight rotations; hand-drawn marks.
- [ ] `fullscreen-chapters`: scroll-snapped full-screen scenes, one message each.
- [ ] `diagonal-flow`: sections meet on diagonals and curves; content follows the slope.
- [ ] `object-hero-3d`: one interactive 3D object (product, logo form) the page orbits around.
- [ ] `cursor-world`: the pointer reveals, lights or distorts; touch has its own equivalent.
- [ ] `kinetic-type`: headlines that move with scroll (scale, slide, scrub), little imagery.
- [ ] `editorial-spread`: magazine spreads, text wrapping around cut-out images, pull quotes huge.
- [ ] `bento-living`: a bento board whose tiles animate and rearrange as you scroll.
- [ ] `map-journey`: a path drawn along the scroll that the content follows (routes, timelines, process).
- [ ] `dark-gallery`: dark room, spot-lit pieces, slow reveals (art, jewellery, wine).
- [ ] `brutal-grid`: raw grid lines, mono type, visible structure, loud colour blocks.
## Acceptance criteria
- [ ] Each concept passes the #3 tests and names its reduced-motion and phone versions concretely.
- [ ] Each lists 3+ blueprints it pairs with and 1+ where it must not be used.
- [ ] A demo page per concept built by hand from the kit (in `packages/agents/stack/demos/` or a storybook-like route) so the recipe is proven before an agent uses it. Screenshot each into the PR.
## Depends on
#3, kit issues #6-#10 (a concept can ship once its components exist).
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Plan key `T4`. Epic: El-SaMa/tekori#19.
