test: bring coverage to 85%, set threshold to 85, reset version to 3.0.11

- Add tests for config, convo_miner, spellcheck, knowledge_graph
- Fix Windows PermissionError in test cleanup (chromadb file locks)
- Add UTF-8 encoding to split_mega_files, entity_registry, hooks_cli
- Fix mcp_server parse_known_args logging for unknown args
- Set coverage threshold to 85 in pyproject.toml and CI
- Reset all version files to 3.0.11

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

mempalace/entity_registry.py

@@ -309,7 +309,7 @@ class EntityRegistry:
 
     def save(self):
         self._path.parent.mkdir(parents=True, exist_ok=True)
-        self._path.write_text(json.dumps(self._data, indent=2))
+        self._path.write_text(json.dumps(self._data, indent=2), encoding="utf-8")
 
     @staticmethod
     def _empty() -> dict: