fix: drop install anyway when nothing can come

Offline with nothing here to copy, Install was removed, and a folder
short of space or read-only then put Install anyway back: a run that
could only fail every file.

install.py

@@ -10428,13 +10428,13 @@ def _plan_rows(state: TuiState) -> list[TuiRow]:
     rows = [TuiRow("install", label)]
     if _offline_only() and not _plan_copies(state, check):
         # Nothing here to copy, and the network refused: Install would
-        # only fail every file.
+        # only fail every file, in this folder or another.
         rows = []
     if state.facts.get("writable") is False or _short_of_space(state, check):
         # Every file would fail alike, or the run would stop before the
         # first one: the way out is another folder.
-        rows = [TuiRow("folder", "Choose another folder"), TuiRow("install", "Install anyway"),
-                *rows[1:]]
+        rows = [TuiRow("folder", "Choose another folder"),
+                *([TuiRow("install", "Install anyway")] if rows else [])]
     if records_selection((state.manifest or {}).get("files", [])) and len(state.systems) > 1:
         rows.append(TuiRow("systems", "Choose systems"))
     rows.append(TuiRow("fromcard", "Copy the BIOS files from your old card or a folder"))

tests/test_install_tui.py

@@ -2212,6 +2212,17 @@ class AuditRoundThree(unittest.TestCase):
         self.assertEqual(press(state, "enter"), [])
         self.assertEqual(state.screen, "folder")
 
+    def test_offline_with_nothing_to_copy_offers_no_install_anyway(self):
+        """Offline with nothing here to copy, Install is removed: a folder
+        short of space then put "Install anyway" back, a run that could
+        only fail every file."""
+        state = checked_state({"free": 1024, "writable": False, "cores": []})
+        with mock.patch.dict(os.environ, {install.OFFLINE_VARIABLE: "1"}):
+            labels = [row.label for row in install.tui_rows(state)]
+        self.assertEqual(labels[0], "Choose another folder")
+        self.assertNotIn("Install anyway", labels)
+        self.assertFalse(any(label.startswith("Install") for label in labels), labels)
+
     FULL_TAIL = [
         "  Checking existing files...",
         "    0/50 present (0 verified, 0 wrong hash)",