feat(games): manually add games (e.g. SPT) with launch + own logs

Some titles never show up in a Steam/Lutris/Heroic scan — standalone mod
launchers like SPT (Single-Player Tarkov), itch.io downloads, hand-installed
executables. Add a user-authored custom-games list (core/customgames.py) shown
alongside the other sources in `rigdoctor games` and the GUI.

Each entry can carry a launch command and a log directory:
  - `rigdoctor games add "SPT" --command .../tarkov.sh` (logs/ auto-detected)
  - `rigdoctor games play "SPT"` launches it under the crash-capture wrapper
    (wrap.run gains an explicit game-name override, since there's no SteamAppId)
  - the diagnostic now feeds the game's own logs to the analysis: gamelogs
    .collect(game=...) tails the registered log dir (SPT's server/launcher logs)
    alongside the kernel log, freshness-scoped by mtime.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_gamelogs.py

@@ -47,6 +47,36 @@ class CollectTests(unittest.TestCase):
             self.assertEqual(gamelogs.collect(), "")
 
 
+class CustomGameLogTests(unittest.TestCase):
+    def test_collect_includes_custom_game_logs(self):
+        tmp = Path(tempfile.mkdtemp())
+        (tmp / "tarkov-latest.log").write_text(">>> Tarkov gone. clean exit")
+        (tmp / "server-latest.log").write_text("SPT server error: mod failed to load")
+        with mock.patch.object(gamelogs, "_proton_logs", return_value=[]), \
+             mock.patch.object(gamelogs, "_steam_console", return_value=None), \
+             mock.patch("rigdoctor.core.customgames.log_dir", return_value=str(tmp)):
+            out = gamelogs.collect(game="SPT")
+        self.assertIn("SPT log", out)
+        self.assertIn("server-latest.log", out)
+        self.assertIn("mod failed to load", out)
+
+    def test_custom_logs_skipped_when_stale(self):
+        tmp = Path(tempfile.mkdtemp())
+        old = tmp / "tarkov-latest.log"
+        old.write_text("an earlier session")
+        old_mtime = time.time() - 3600
+        os.utime(old, (old_mtime, old_mtime))
+        with mock.patch.object(gamelogs, "_proton_logs", return_value=[]), \
+             mock.patch.object(gamelogs, "_steam_console", return_value=None), \
+             mock.patch("rigdoctor.core.customgames.log_dir", return_value=str(tmp)):
+            self.assertEqual(gamelogs.collect(since=time.time() - 60, game="SPT"), "")
+
+    def test_no_game_means_no_custom_logs(self):
+        with mock.patch.object(gamelogs, "_proton_logs", return_value=[]), \
+             mock.patch.object(gamelogs, "_steam_console", return_value=None):
+            self.assertEqual(gamelogs.collect(), "")  # game=None → custom lookup skipped
+
+
 class SinceScopingTests(unittest.TestCase):
     def test_since_filter_keeps_window_only(self):
         text = (