CUGA: Propagate multi-user context (user_id, namespace_id, session_id) to Evolve MCP server

[visahak]

Problem

ALTK-Evolve's MCP server already supports multi-user parameters (user_id, namespace_id, session_id) across get_guidelines, save_trajectory, and get_entities. However, the CUGA agent never sends these values — all Evolve interactions appear as "default" user with no tenant or session context.
Root causes:

1. event_stream() in server/main.py receives user_id from the authenticated request but never assigns it to local_state.user_id
2. CugaLiteState lacks a user_id field, so the subgraph cannot propagate user identity
3. EvolveIntegration.get_guidelines() and save_trajectory() don't accept or forward any context parameters

Will submit a PR in cuga.

Follows up issue #225