feat: T6 wave 3 – treatment books from lot, label print lock, restricted zone, authority notices

- Treatments book their dose from a medicine lot (delta booking on edit,
  bulk all-or-nothing, idempotent); Bestandsbuch columns from the lot,
  FEHLT exactly where treatmentLogGaps reports a gap; Bestandsbuch export
  needs veterinary-medicines:read.
- Label printing: 409 LABEL_PARTICULARS_MISSING on gaps, proof print with
  watermark, PRINT audit before the PDF, check endpoints; digit rules only
  from the seeded ComplianceSettings row (fail closed).
- Restricted zone (Berlin day): create, update, move, merge and CSV import
  blocked inside an active restriction; override with reason and
  compliance:manage, audited, never stored on the colony; split, harvest
  and dissolve stay free; restriction details only with compliance:read.
- Authority notices: settings, herd snapshot, registration/herd change/TSK
  notices with one open draft per kind under the settings lock.
- Label check refinements (geometric reading order, number|unit pairs).
- ARCHITECTURE.md §12.6–12.8, Annahmen 71–77; spec §5.6 Berlin day.

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

ApiCore-Backend/src/label-templates/label-proof-watermark.ts

@@ -0,0 +1,49 @@
+export const PROOF_WATERMARK_TEXT = 'MUSTER – nicht verkaufsfähig';
+
+const WATERMARK_COLOR = '#808080';
+const WATERMARK_OPACITY = 0.5;
+const WATERMARK_FONT = 'Helvetica-Bold';
+// The text runs along the label's diagonal; this share of it is covered.
+const DIAGONAL_COVERAGE = 0.8;
+// Never taller than this share of the label's height.
+const MAX_HEIGHT_SHARE = 0.5;
+const MEASURE_SIZE_PT = 10;
+
+/**
+ * Draws the proof stamp "MUSTER – nicht verkaufsfähig" over one label: grey,
+ * half opaque, rotated along the label's diagonal and centred. Called once
+ * per label, after its content. The graphics state is restored, so nothing
+ * leaks into the next label.
+ */
+export function drawProofWatermark(
+  doc: PDFKit.PDFDocument,
+  originX: number,
+  originY: number,
+  widthPt: number,
+  heightPt: number,
+): void {
+  const centerX = originX + widthPt / 2;
+  const centerY = originY + heightPt / 2;
+  const angleDeg = (Math.atan2(heightPt, widthPt) * 180) / Math.PI;
+
+  doc.save();
+  doc.font(WATERMARK_FONT).fontSize(MEASURE_SIZE_PT);
+  const widthAtMeasureSize = doc.widthOfString(PROOF_WATERMARK_TEXT);
+  const targetWidth = Math.hypot(widthPt, heightPt) * DIAGONAL_COVERAGE;
+  const fontSize = Math.min(
+    (MEASURE_SIZE_PT * targetWidth) / widthAtMeasureSize,
+    heightPt * MAX_HEIGHT_SHARE,
+  );
+  const textWidth = (widthAtMeasureSize * fontSize) / MEASURE_SIZE_PT;
+
+  doc.fillColor(WATERMARK_COLOR).fillOpacity(WATERMARK_OPACITY);
+  doc.rotate(-angleDeg, { origin: [centerX, centerY] });
+  doc.fontSize(fontSize);
+  doc.text(
+    PROOF_WATERMARK_TEXT,
+    centerX - textWidth / 2,
+    centerY - fontSize / 2,
+    { lineBreak: false },
+  );
+  doc.restore();
+}