[FEATURE] Support multi-user isolation in temporal graph facts

[kishan0725]

Problem

Temporal facts currently have no built-in user isolation mechanism. All facts exist in a global namespace, making it unsuitable for multi-user systems where each user's facts should be isolated.

Impact

• Cannot use temporal facts in multi-user applications
• All users share same fact namespace
• Data conflicts between users
• No privacy/isolation guarantees

Proposed Solution

Add user_id Column in the temporal_facts table

MCP Changes

The tools should support accepting userId for storage and retrieval and pass it to the required service layer.

Benefits:

• Native database-level isolation
• Efficient filtering (indexed)
• Matches HSG memory model
• Clear and explicit

Code of Conduct

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