feat(ai): render Markdown + feed game/Proton/Steam logs to the AI — 0.28.0

1) The explanation popup rendered raw Markdown (### / **). Switched to
   QTextEdit.setMarkdown and told the model to answer in Markdown.
2) On "Explain with AI", also collect recent Proton (~/steam-*.log) and Steam
   console logs (core/gamelogs.py — tail-read, size-bounded) and include them in
   the prompt so the model can correlate log errors with findings and pinpoint
   when things went wrong. Reference-fact matching runs over the logs too.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_gamelogs.py

@@ -0,0 +1,49 @@
+"""Tests for M14 game/Proton/Steam log collection."""
+
+import tempfile
+import unittest
+from pathlib import Path
+from unittest import mock
+
+from rigdoctor.core import gamelogs
+
+
+class TailTests(unittest.TestCase):
+    def test_tail_returns_last_bytes(self):
+        path = Path(tempfile.mkdtemp()) / "x.log"
+        path.write_text("A" * 100 + "TAIL")
+        out = gamelogs._tail(path, 4)
+        self.assertEqual(out, "TAIL")
+
+    def test_tail_short_file(self):
+        path = Path(tempfile.mkdtemp()) / "x.log"
+        path.write_text("short")
+        self.assertEqual(gamelogs._tail(path, 9999), "short")
+
+    def test_tail_missing(self):
+        self.assertEqual(gamelogs._tail(Path("/nope/x.log"), 10), "")
+
+
+class CollectTests(unittest.TestCase):
+    def test_collect_includes_proton_and_steam(self):
+        tmp = Path(tempfile.mkdtemp())
+        proton = tmp / "steam-570.log"
+        proton.write_text("err: vkd3d device lost")
+        console = tmp / "console-linux.txt"
+        console.write_text("Game removed AppID 570 ... exit")
+        with mock.patch.object(gamelogs, "_proton_logs", return_value=[proton]), \
+             mock.patch.object(gamelogs, "_steam_console", return_value=console):
+            out = gamelogs.collect()
+        self.assertIn("Proton log", out)
+        self.assertIn("vkd3d", out)
+        self.assertIn("Steam log", out)
+        self.assertIn("exit", out)
+
+    def test_collect_empty_when_none(self):
+        with mock.patch.object(gamelogs, "_proton_logs", return_value=[]), \
+             mock.patch.object(gamelogs, "_steam_console", return_value=None):
+            self.assertEqual(gamelogs.collect(), "")
+
+
+if __name__ == "__main__":
+    unittest.main()