fix: harden events log — non-dict ring entries, off-loop journal reads, no default-config singleton

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

hbd/server/http.py

@@ -389,10 +389,14 @@ async def start(
 
         ej = journal_mod.get_events_journal(config)
         if ej.enabled and ej.journal_path.is_file():
-            events, more = journal_mod.read_events(
-                ej.journal_dir, ej.journal_file,
-                limit=limit, before=before, host=host_f, level=level_f, q=q_f,
-                predicate=visible,
+            # File scan can be large; keep it off the loop that services UDP/WS
+            events, more = await asyncio.get_running_loop().run_in_executor(
+                None,
+                lambda: journal_mod.read_events(
+                    ej.journal_dir, ej.journal_file,
+                    limit=limit, before=before, host=host_f, level=level_f, q=q_f,
+                    predicate=visible,
+                ),
             )
         else:
             # Journal disabled or not yet written: serve the in-memory ring