GET /api/cma/alignment/tree queried all active KPIs without entity_id filter,
so switching the three alignment modes showed other tenants' KPIs.
Add get_entity_id dependency and filter KPIDefinition by entity_id.
Three mode builders (_build_vertical_tree/_build_horizontal_tree/_build_bsc_chain) unchanged.
Auth semantics unchanged; cross-entity explicit entity_id still returns 403.
Test: tests/test_alignment_entity_isolation_20260918.py (3 modes x both directions, 403, 401).