fix(retrieval): enforce project-scoped context boundaries

src/atocore/config.py

@@ -46,6 +46,8 @@ class Settings(BaseSettings):
     # All multipliers default to the values used since Wave 1; tighten or
     # loosen them via ATOCORE_* env vars without touching code.
     rank_project_match_boost: float = 2.0
+    rank_project_scope_filter: bool = True
+    rank_project_scope_candidate_multiplier: int = 4
     rank_query_token_step: float = 0.08
     rank_query_token_cap: float = 1.32
     rank_path_high_signal_boost: float = 1.18