fix(deploy-win): extract ISO with 7z so no-prompt boot patch works

xorriso -extract reads the ISO9660 name tree, which on a Windows ISO has
no Rock Ridge — names come back upper-cased/truncated, so the
`efi/microsoft/boot/efisys_noprompt.bin` lookup failed ("missing from
ISO") and a repack from that tree would corrupt Windows' long file names.

Extract with 7z instead (reads the UDF/Joliet tree, preserving the real
lower-case paths), excluding 7z's synthetic `[BOOT]` dump. Verified
end-to-end on the cached 26100.32860 ISO: 7z extract → xorriso repack
yields a 5 GB ISO with autounattend.xml + post-install.ps1 at the root and
efisys_noprompt.bin as the UEFI El Torito image (no boot prompt).

Also: cap the Joliet volume id at 16 chars (silence xorriso warning), add
a 7z preflight check, and add p7zip-full to setup-host-linux.sh.

src/ci_orchestrator/commands/template.py

@@ -2174,6 +2174,7 @@ def template_deploy_win(
             (f"vmrun found: {vmrun}", bool(shutil.which(vmrun) or Path(vmrun).is_file())),
             (f"vmware-vdiskmanager found: {vdisk_mgr}", Path(vdisk_mgr).is_file()),
             ("xorriso in PATH", shutil.which("xorriso") is not None),
+            ("7z in PATH", any(shutil.which(n) for n in ("7z", "7za", "7zr"))),
             (f"VMware Tools ISO: {tools_iso}", tools_iso.is_file()),
         ]
         for label, ok in checks:

src/ci_orchestrator/winimage/iso_patch.py

@@ -30,6 +30,14 @@ def _require_xorriso() -> str:
     return exe
 
 
+def _require_7z() -> str:
+    for name in ("7z", "7za", "7zr"):
+        exe = shutil.which(name)
+        if exe is not None:
+            return exe
+    raise click.ClickException("7z not found. Install p7zip-full.")
+
+
 def _read_volid(base_iso: Path) -> str:
     """Read the ISO volume id (label); fall back to a sane default."""
     label = ""
@@ -42,7 +50,8 @@ def _read_volid(base_iso: Path) -> str:
             check=False,
         )
         label = proc.stdout.strip()
-    return (label or "WINSERVER")[:32]
+    # Joliet volume ids are capped at 16 chars; longer ids make xorriso warn.
+    return (label or "WINSERVER")[:16]
 
 
 def _check_free_space(base_iso: Path, work_parent: Path) -> None:
@@ -66,6 +75,7 @@ def patch_iso(
 ) -> Path:
     """Inject answer files + no-prompt boot into ``base_iso`` → ``out_iso``."""
     xorriso = _require_xorriso()
+    sevenz = _require_7z()
     if not base_iso.is_file():
         raise click.ClickException(f"base ISO not found: {base_iso}")
 
@@ -79,12 +89,19 @@ def patch_iso(
     tree.mkdir(parents=True)
 
     try:
+        # Extract with 7z (reads the UDF/Joliet tree) so the long, lower-case
+        # Windows paths survive. xorriso's -extract uses the ISO9660 name tree
+        # (upper-case / truncated, no Rock Ridge on Windows ISOs), which both
+        # breaks the efisys_noprompt.bin lookup and would corrupt Windows file
+        # names in the repacked image. ``[BOOT]`` is 7z's synthetic El Torito
+        # dump — excluded so it does not pollute the tree.
         click.echo(f"  [iso] extracting base ISO: {base_iso.name}")
         subprocess.run(
-            [xorriso, "-osirrox", "on", "-indev", str(base_iso), "-extract", "/", str(tree)],
+            [sevenz, "x", str(base_iso), f"-o{tree}", "-y", "-bd", "-x![BOOT]"],
             check=True,
+            stdout=subprocess.DEVNULL,
         )
-        # Extracted files are read-only; make the tree writable so we can add files.
+        # Extracted files may be read-only; make the tree writable so we can add files.
         subprocess.run(["chmod", "-R", "u+w", str(tree)], check=True)
 
         efi_boot = tree / _EFI_BOOT_NOPROMPT