add cover layout for A5 book including front and spine design

cover.typ

@@ -0,0 +1,46 @@
+// Cover spread: back + spine + front as one page
+// A5 = 148mm x 210mm, spine ~2mm for 30 pages at 80gsm
+// Total width = 148 + 2 + 148 = 298mm
+// Add 3mm bleed on each edge for print
+// Background image size: 304mm x 216mm (298+6 x 210+6) = 3591px x 2551px at 300dpi
+
+#let page-w = 148mm
+#let page-h = 210mm
+#let spine-w = 2mm
+#let bleed = 3mm
+
+#set page(
+  width: page-w * 2 + spine-w + bleed * 2,
+  height: page-h + bleed * 2,
+  margin: 0pt,
+  fill: black,
+)
+#set text(font: "New Computer Modern")
+
+// Front cover: title + subtitle centered on the right half
+#place(
+  top + left,
+  dx: bleed + page-w + spine-w,
+  dy: bleed,
+  box(
+    width: page-w,
+    height: page-h,
+    align(center + horizon,
+      [
+        #text(size: 18pt, fill: white, weight: "bold", tracking: 2pt)[QUIS SUMUS]
+        #v(0.5em)
+        #text(size: 8pt, fill: gray, style: "italic")[Existence, immortality, and the irrelevance of both]
+      ]
+    )
+  )
+)
+
+// Spine: "Gabriel Kaszewski" rotated
+#place(
+  top + left,
+  dx: bleed + page-w + spine-w / 2 - 2pt,
+  dy: page-h / 2 + bleed,
+  rotate(-90deg,
+    text(size: 4pt, fill: white, tracking: 1pt)[GABRIEL KASZEWSKI]
+  )
+)