fix: Update ISO download to Debian 13.0.0 release

Updates ISO download URL to use:
- Primary: Debian 13.0.0 released ISO
- Fallback: Testing branch ISO
Removes daily builds which are too unstable

💘 Generated with Crush

Assisted-by: Gemini 2.5 Flash via Crush <crush@charm.land>

build-iso.sh

@@ -35,18 +35,14 @@ docker run --rm \
         echo "Downloading Debian 13 Trixie Netboot ISO..."
         cd /build/iso-tmp
 
-        # Use daily builds for Debian 13 (trixie) since stable ISO not available yet
+        # Download Debian 13 (trixie) released ISO
         wget -q --show-progress \
             -O debian-trixie-amd64-netinst.iso \
-            https://cdimage.debian.org/debian-cd/daily-builds/amd64/iso-cd/debian-daily-amd64-netinst.iso || \
-        # Fallback to testing
+            https://cdimage.debian.org/debian-cd/13.0.0/amd64/iso-cd/debian-13.0.0-amd64-netinst.iso || \
+        # Fallback to testing if 13.0.0 not available
         wget -q --show-progress \
             -O debian-trixie-amd64-netinst.iso \
-            https://cdimage.debian.org/debian-cd/testing/amd64/iso-cd/debian-testing-amd64-netinst.iso || \
-        # Fallback to current stable (bookworm/sid)
-        wget -q --show-progress \
-            -O debian-trixie-amd64-netinst.iso \
-            https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-sid-amd64-netinst.iso
+            https://cdimage.debian.org/debian-cd/testing/amd64/iso-cd/debian-testing-amd64-netinst.iso
 
         echo ""
         echo "✅ ISO downloaded"