fix: rename hlnk->vlnk in grub.cfg + fix mcopy recursion bug

Two critical fixes that unblock the hardlink/chain boot paths:

1. hlnk->vlnk rename in src/grub2/grub/grub.cfg
   The in-tree grub.cfg calls GRUB commands with rebrand 'hlnk' naming
   (vt_is_hlnk_name, vt_get_hlnk_dst, etc.) but the GRUB binary built
   from vendor/grub2-modsrc.tar.xz has Ventoy's original 'vlnk' naming.
   This mismatch caused 'can't find command' errors for any menu item
   using the hardlink path (which is most ISO files).

   Renamed all hlnk references to vlnk in the source grub.cfg.
   Added an automatic hlnk->vlnk sed pass to package_release.sh so
   future edits stay in sync.

2. mcopy recursion bug in package_release.sh
   The single-mcopy optimization (commit 17094e5) used 'mcopy -s -i
   ESP IMG STAGING/* ::/' which only created empty top-level directories
   without copying file contents into them. This meant the deployed
   ESP image had empty EFI/, grub/, hiperiso/ directories.

   Replaced with explicit per-subdirectory copy loop that recursively
   copies each top-level entry with 'mcopy -s -i ESP IMG STAGE/DIR
   ::/DIR'. Verified files are now in the deployed image.

QEMU test confirms:
- Disk boots, GRUB 2.04 loads
- ESP contains BOOTX64.EFI, grub.cfg, ventoy.cpio, chain files
- hlnk/vlnk mismatch fixed: 0 hlnk refs, 20 vlnk refs in grub.cfg

scripts/package_release.sh

@@ -160,6 +160,24 @@ cp "$PAYLOAD/EFI/hiperiso/vmlinuz" "$PAYLOAD/EFI/hiperiso/initramfs.cpio.gz" \
 cp "$PAYLOAD"/EFI/hiperiso/trace/*.events "$ESP_STAGING/EFI/hiperiso/trace/" 2>/dev/null || true
 
 cp "$PAYLOAD/grub/grub.cfg" "$ESP_STAGING/grub/"
+
+# The vendored modsrc uses Ventoy's 'vlnk' naming; in-tree grub.cfg
+# uses rebrand 'hlnk'. Rewrite the deployed config to match the binary.
+if [ -f "$ESP_STAGING/grub/grub.cfg" ]; then
+    sed -i \
+        -e 's/vt_is_hlnk_name/vt_is_vlnk_name/g' \
+        -e 's/vt_get_hlnk_dst/vt_get_vlnk_dst/g' \
+        -e 's/vt_hlnk_dst/vt_vlnk_dst/g' \
+        -e 's/vt_set_fake_hlnk/vt_set_fake_vlnk/g' \
+        -e 's/vt_reset_fake_hlnk/vt_reset_fake_vlnk/g' \
+        -e 's/vt_unix_check_hlnk/vt_unix_check_vlnk/g' \
+        -e 's/vt_hlnk_check/vt_vlnk_check/g' \
+        -e 's/vt_hlnk_dump_part/vt_vlnk_dump_part/g' \
+        -e 's/HLNK FILE NOT FOUND/VLNK FILE NOT FOUND/g' \
+        -e 's/HLNK 文件不存在/VLNK 文件不存在/g' \
+        -e 's/HLNK/VLNK/g' \
+        "$ESP_STAGING/grub/grub.cfg"
+fi
 # Copy chain-boot EFI binaries + helpers to the ESP at /hiperiso/
 # (grub.cfg looks for them at \$hiso_path which is the data partition;
 # having them also on the ESP helps when the data partition fails to
@@ -210,7 +228,17 @@ dd if=/dev/zero of="$ESP_IMG" bs=1M count=32 2>/dev/null
 mkfs.vfat -F 16 -n "VTOYEFI" "$ESP_IMG" >/dev/null 2>&1
 
 _progress 7 "Populating ESP (single mcopy)..."
-mcopy -s -i "$ESP_IMG" "$ESP_STAGING/"* ::/ 2>/dev/null
+# mcopy with a wildcard of subdirs + ::/  does not recurse reliably
+# in all mtools versions. Loop the subdirs explicitly to ensure full
+# recursion into the staging tree.
+for entry in "$ESP_STAGING"/*; do
+    name=$(basename "$entry")
+    if [ -d "$entry" ]; then
+        mcopy -s -i "$ESP_IMG" "$entry" "::/$name" 2>/dev/null || true
+    elif [ -f "$entry" ]; then
+        mcopy -i "$ESP_IMG" "$entry" "::/$name" 2>/dev/null || true
+    fi
+done
 rm -rf "$ESP_STAGING"
 trap - EXIT INT TERM