fix(lora): a cached layout needs the same home folder; give the rebuild poll its time (#362)

Final review follow-ups: the folder guard compares against the home folder,
so a cache hit now also needs Path.home() unchanged. TESTING.md says the
configured-path rule runs on the cache's result and that a non-UTF-8
sidecar is skipped.

CI: 'Rebuild all is explicit...' (webkit) polled the job for the default
5 s while it regenerated 24 previews; the failure screenshot shows 12 of 24
done at the deadline on the busy runner (0.17 s locally). The poll now
allows 30 s for that real work.

tests/test_lora_layout_cache.py

@@ -164,6 +164,17 @@ class ValidationTests(CacheTestCase):
         self.assertEqual(self.resolved, ["", "other"])
         self.assertEqual(len(self.loaded), 2)
 
+    def test_a_different_home_folder_reloads(self):
+        # The folder guard compares against the home folder: a cached layout
+        # must not outlive a change of it.
+        home = {"value": str(self.tmp / "home-a")}
+        cache = self.cache(home=lambda: home["value"])
+        cache.get("")
+        cache.get("")
+        home["value"] = str(self.tmp / "home-b")
+        cache.get("")
+        self.assertEqual(len(self.loaded), 2)
+
     def test_configured_path_is_stripped_for_the_key_and_the_resolver(self):
         cache = self.cache()
         cache.get("  x ")