feat: sheet templates, margin profiles and delivering the sheet

Seeds the four sheet setups Till actually prints (Kita set, small school set,
full passport sheet, two 10x7,5 on 10x15 paper). A multi-format template
applied to a single image clones it into every format, so one click yields the
whole set. Margin gets one-click borderless / 5 mm / 10 mm profiles, and the
finished PDF can be pushed to Picdrop, the NAS or any extra target.

CHANGELOG.md

@@ -33,6 +33,12 @@ All notable changes to Klarbild are documented here. Newest first.
   button-driven, returns an A4 PDF), and the MCP tools `exact_size` / `print_sheet`.
 - **API** — `POST /api/print/single`, `GET /api/print/single?size=…` (mm → px calculator),
   `POST /api/print/sheet`, `GET|POST|DELETE /api/print/presets`. Documented in `/llms.txt`.
+- **Seeded sheet templates** — "Kita-Satz (A4)", "Schulsatz klein (A4)", "Passbildbogen 35×45 (A4)"
+  and "2 × 10×7,5 auf Fotopapier 10×15". Loading a multi-format template with a single image
+  clones that image into every format, so one click produces the whole set.
+- **Margin profiles** — borderless (0 mm), standard (5 mm) and safe (10 mm) as one-click buttons.
+- **Deliver the sheet** — the finished PDF can additionally be pushed to Picdrop, the NAS or any
+  extra delivery target (`deliver` in the sheet request).
 - **Tests** — `tests/printlayout.test.ts` (`npm test`) covers size parsing, exact mm → px,
   non-overlap, margins, bleed spacing, mark geometry and multi-sheet paging.