Linked Issue

Closes #3907

Description

Context — earlier PR (#4184)
PR #4184 fixed _remove_spaces_from_entities only in graph_memory.py (Neo4j) by skipping empty/incomplete relation dicts from LLM output, which removed KeyError when the model returned values like [{}] or dicts missing source / relationship / destination and the code implementation was perfect only.
Why this PR
The same helper logic existed in four places (graph_memory, memgraph_memory, kuzu_memory, neptune/base). #4184 only updated Neo4j, so Memgraph, Kuzu, and Neptune could still hit the same failure mode. This PR:

• Adds a single implementation: mem0.memory.utils.remove_spaces_from_entities.
• Has each backend delegate to it with the right behavior: sanitize_relationship=True for Neo4j/Memgraph (existing Cypher relationship sanitizer), False for Kuzu/Neptune (plain lower + underscores), matching what each file did before.
• Keeps validation in one place (DRY) so future fixes apply everywhere.
  Closing fix: skip malformed entities in _remove_spaces_from_entities #4184
  fix: skip malformed entities in _remove_spaces_from_entities #4184 can be closed as superseded by this PR: it solves the same class of bug across all graph backends and includes unit tests for the shared helper. Thank you to the fix: skip malformed entities in _remove_spaces_from_entities #4184 author for the original Neo4j fix and tests.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• Refactor (no functional changes)

Breaking Changes

N/A

Test Coverage

• I added/updated unit tests

Added tests/memory/test_memory_utils.py covering malformed lists, both sanitization modes, and non-dict entries. Ran:
pytest tests/memory/test_memory_utils.py tests/memory/test_neo4j_cypher_syntax.py tests/memory/test_memgraph_memory.py -v

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have added tests that prove my fix/feature works
• New and existing tests pass locally
• I have updated documentation if needed