feat: count game data apart from BIOS files

The installer knew BIOS files from game data and no count showed it.
The plan, the line menu and the result count them apart for a list that
marks game data, the plan gets a game data row and the menu a g key,
each toggling it in one press, and one sentence says what game data is.

tests/test_install_tui.py

@@ -6852,6 +6852,73 @@ class LineModeAndScreenDecideAlike(unittest.TestCase):
         self.assertEqual(ark.screen, "folder")
         self.assertEqual(install._tui_card_bound(ark)[0], "ArkOS")
 
+    # The owner's request of 2026-10-27: BIOS files and game data counted
+    # apart, the game data choice on the plan itself and in the menu.
+
+    def game_list(self) -> tuple[Path, list]:
+        files = [self.entry("gba_bios.bin", b"gba", ["nintendo-gba"]),
+                 self.entry("doom/doom1.wad", b"wad" * 10, ["doom"], category="game_data")]
+        return self.listing("retroarch", files, categorized=True), files
+
+    def test_line_mode_counts_game_data_apart_and_g_leaves_it_out(self):
+        listing, _files = self.game_list()
+        args = dict(manifest=listing, dest=self.here, declared_only=False, dry_run=True)
+        text, asked = self.line_run(_args(**args), ["g", ""])
+        self.assertIn("1 BIOS file (3 B) and 1 game data file (30 B).", text)
+        self.assertIn("g) leave out the 1 game data file (30 B), game data: files a game or "
+                      "a game engine reads, of no use to the other cores", text)
+        after = text[text.index("Counted again"):]
+        self.assertIn("RetroArch: 1 file, 3 B.", after)
+        self.assertIn("g) keep the 1 game data file", after)
+        self.assertIn("--no-game-data", after)
+        self.assertIn("Left out as game data", after)
+        self.assertNotIn("doom1.wad would", after)
+
+    def test_the_plan_counts_game_data_apart_and_one_press_leaves_it_out(self):
+        state = checked_state()
+        manifest = json.loads(json.dumps(state.manifest))
+        for entry in manifest["files"]:
+            if entry["dest"] == "pcsx/extra.bin":
+                entry["category"] = "game_data"
+        state.manifest = manifest
+        text = " ".join(" ".join(install.tui_view(state, 80, 24)).split())
+        self.assertIn("3 BIOS files (1.0 MB) and 1 game data file (4 B). Game data: files a "
+                      "game or a game engine reads, of no use to the other cores.", text)
+        rows = install.tui_rows(state)
+        row = next(row for row in rows if row.action == "gamedata")
+        self.assertIn("kept, leave out", row.label)
+        state.focus["plan"] = rows.index(row)
+        effects = install.tui_update(state, Key("enter"))
+        self.assertTrue(state.no_game_data)
+        self.assertEqual(effects, [("run", "check")])
+        self.assertIn(("--no-game-data", None), install.tui_flags(state))
+
+    def test_the_result_counts_game_data_apart_in_both_modes(self):
+        state = _installed_state(Path("/x/system"))
+        state.manifest = {**state.manifest, "files": [
+            *state.manifest["files"],
+            {"dest": "doom/doom1.wad", "size": 30, "category": "game_data", "cores": None}]}
+        state.finished = [("scph5500.bin", True, ""), ("doom/doom1.wad", True, "")]
+        _title, lines = install.tui_outcome(state)
+        self.assertIn("Installed: 1 BIOS file and 1 game data file.", lines)
+        listing, _files = self.game_list()
+        backup = self.root / "old"
+        (backup / "doom").mkdir(parents=True)
+        (backup / "gba_bios.bin").write_bytes(b"gba")
+        (backup / "doom" / "doom1.wad").write_bytes(b"wad" * 10)
+        args = _args(manifest=listing, dest=self.here, offline=True, declared_only=False,
+                     no_input=True)
+        setattr(args, "from", [backup])
+        real = io.StringIO()
+        install.LOCAL.reset()
+        self.addCleanup(install.LOCAL.reset)
+        with mock.patch.object(install, "detect_os", return_value="linux"), \
+                contextlib.redirect_stdout(io.StringIO()), \
+                contextlib.redirect_stderr(io.StringIO()):
+            install._install(args, real)
+        self.assertIn("Done. 2 files installed", real.getvalue())
+        self.assertIn("Installed: 1 BIOS file and 1 game data file.", real.getvalue())
+
     def test_line_mode_says_the_card_it_found_and_names_its_folder(self):
         onion = self.card("ONION", "Onion")
         with mock.patch.object(install, "_mounted_cards", return_value=[onion]), \
@@ -7739,10 +7806,13 @@ class AuditSeventeenAndTen(unittest.TestCase):
     def test_the_docs_say_what_the_installer_does(self):
         """code_audit_17 P3-7."""
         page = (REPO_ROOT / "wiki" / "installer.md").read_text(encoding="utf-8")
-        menu = page[page.index("RetroArch: 8069 files, 6.5 GB."):]
+        menu = page[page.index("RetroArch: 8348 files, 7.1 GB."):]
         menu = menu[:menu.index("```")]
         self.assertIn("BIOS folder:", menu)
         self.assertIn("f) copy from a folder or an old card", menu)
+        # The owner's request of 2026-10-27: game data counted apart, g.
+        self.assertIn("3259 BIOS files (4.4 GB) and 5089 game data files (2.7 GB).", menu)
+        self.assertIn("g) leave out the 5089 game data files", menu)
         env = page[page.index("## Environment overrides"):]
         self.assertIn("`TERMINFO`", env)
         self.assertIn("`TERMINFO_DIRS`", env)