Completes the last deferred item from ROADMAP §0: entities recognized as
the same real-world concept across enabled streams (e.g. srcip in both a
firewall and an IIS stream) now share baseline knowledge of entity
presence/age and known relationship-target values, instead of each stream
learning it cold. Implemented additively (synthetic shared_entity:<group>
namespace in the existing baseline.py tables, no schema migration), scoped
to entity presence + relationship known-values only — per-stream
distribution baselines stay untouched. Also fixes a latent alias-map
collision bug found while building this (ALIAS_CANONICAL_BY_FIELD let
"context" silently steal "hostname"/"dns_query" from their own canonical
groups).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
