A triple with valid_to < valid_from satisfies neither of the temporal
filter clauses in query_entity():
valid_from <= as_of AND valid_to >= as_of
so the triple is invisible to every query — silently corrupt. Reject
at write time with a clear error instead of letting bad data pile up
in the SQLite store.
The guard only fires when both bounds are present; open intervals
(only valid_from or only valid_to) are still accepted, and same-day
intervals (valid_from == valid_to, point-in-time facts) are explicitly
allowed.
- Switch CI install step from `pip install -r requirements.txt` to
`pip install -e ".[dev]"` since requirements.txt was removed
- Add noqa: E402 to intentionally-late imports in conftest.py
(HOME must be isolated before mempalace imports)
- Remove unused KnowledgeGraph import in test_knowledge_graph.py
- Apply ruff formatting to test files