label OCI manager Apps as a Technology Preview, as Proxmox VE does

- OCI manager Apps carries the Technology Preview label that Proxmox VE gives to application containers from OCI images, in the main menu, the engine windows, the menu search, the message at the end of each installation, the release notes and the documentation.
- The documentation explains that the label refers to the Proxmox VE support it runs on, not to the ProxMenux engine, and stays until Proxmox VE marks it as stable.
- Spanish for the new message; the other languages are left to the translation bot.

.github/scripts/tests/test_oci_pve_version_gate.py

@@ -0,0 +1,46 @@
+"""OCI manager Apps opens only on Proxmox VE 9.1 or later, the first release
+that runs OCI images as LXC containers."""
+from pathlib import Path
+import re
+import subprocess
+import tempfile
+import unittest
+
+ROOT = Path(__file__).resolve().parents[3]
+LAUNCHER = ROOT / 'scripts/oci/oci_manager_apps.sh'
+
+
+class OciPveVersionGateTests(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        text = LAUNCHER.read_text(encoding='utf-8')
+        cls.function = re.search(r'^pve_supports_oci\(\) \{\n.*?^\}\n', text, re.M | re.S).group(0)
+        cls.text = text
+
+    def supported(self, version):
+        with tempfile.TemporaryDirectory() as folder:
+            fake = Path(folder, 'pveversion')
+            # Without Proxmox the command is missing: a stand-in that fails hides the host's own.
+            fake.write_text('#!/bin/sh\nexit 127\n' if version is None else
+                            f'#!/bin/sh\necho "pve-manager/{version}/b9984c6d90a4bd80 (running kernel: 6.17)"\n')
+            fake.chmod(0o755)
+            result = subprocess.run(['bash', '-c', f'PATH={folder}:/usr/bin:/bin\n{self.function}pve_supports_oci'],
+                                    capture_output=True, text=True)
+        return result.returncode == 0
+
+    def test_versions_from_9_1_open_it(self):
+        for version in ('9.1.0', '9.1.4', '9.2.2', '10.0.1'):
+            with self.subTest(version=version):
+                self.assertTrue(self.supported(version))
+
+    def test_older_versions_and_hosts_without_proxmox_do_not(self):
+        for version in ('8.4.1', '9.0.11', None):
+            with self.subTest(version=version):
+                self.assertFalse(self.supported(version))
+
+    def test_it_is_checked_before_anything_is_installed(self):
+        self.assertLess(self.text.index('if ! pve_supports_oci; then'), self.text.index('ensure_oci_dependencies || exit 1'))
+
+
+if __name__ == '__main__':
+    unittest.main()