feat(labels): cut marks in the sheet margin for trimming with a paper cutter

Label sheets printed on plain A4 are cut with a lever paper cutter. Each
template can now print small hairline cut marks in the sheet margin: one
at both ends of every cut line (left/right edge of each column, top/bottom
edge of each row), 1 mm away from the label and never closer than 2 mm to
the paper edge, so they print on normal printers and never touch a label.
Labels without a gap share one mark. Marks are drawn on every sheet for
the full grid, since the cutter cuts across the whole sheet.

On by default (new column cropMarks, default true); switch it off in the
template designer for pre-die-cut label sheets.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

ApiCore-Frontend/src/lib/label-templates/types.ts

@@ -81,6 +81,7 @@ export interface LabelTemplate {
   marginLeftMm: number;
   gapXMm: number;
   gapYMm: number;
+  cropMarks: boolean;
   isDefault: boolean;
   active: boolean;
   createdAt: string;
@@ -98,6 +99,7 @@ export interface CreateLabelTemplateInput {
   marginLeftMm?: number;
   gapXMm?: number;
   gapYMm?: number;
+  cropMarks?: boolean;
   isDefault?: boolean;
 }
 
@@ -112,5 +114,6 @@ export interface UpdateLabelTemplateInput {
   marginLeftMm?: number;
   gapXMm?: number;
   gapYMm?: number;
+  cropMarks?: boolean;
   isDefault?: boolean;
 }