feat(phase-11): implement Red/Blue business logic services (T-106, T-107, T-108)

T-106: Create test_workflow_service.py with state-machine transitions for the complete test lifecycle (draft -> red_executing -> blue_evaluating -> in_review -> validated/rejected), dual validation by Red/Blue leads, and reopen capability with field cleanup.

T-107: Update status_service.py to use detection_result from Blue Team instead of legacy result field, and differentiate between partial progress (some validated) vs all-in-progress states.

T-108: Create atomic_import_service.py that downloads the Atomic Red Team repo as a ZIP (avoiding API rate limits), parses all atomics YAML files, and creates idempotent TestTemplate records mapped to MITRE techniques.

Includes validation tests for all three tasks (19 checks total).

backend/app/models/evidence.py

@@ -1,11 +1,12 @@
 import uuid
 from datetime import datetime
 
-from sqlalchemy import Column, String, DateTime, ForeignKey
+from sqlalchemy import Column, String, Text, DateTime, ForeignKey, Enum
 from sqlalchemy.dialects.postgresql import UUID
 from sqlalchemy.orm import relationship
 
 from app.database import Base
+from app.models.enums import TeamSide
 
 
 class Evidence(Base):
@@ -14,6 +15,9 @@ class Evidence(Base):
     
     Files are stored in MinIO, and this model tracks the file location,
     integrity hash, and upload metadata.
+    
+    The ``team`` field distinguishes whether this evidence was uploaded by
+    Red Team (attack evidence) or Blue Team (detection evidence).
     """
     __tablename__ = "evidences"
 
@@ -24,6 +28,8 @@ class Evidence(Base):
     sha256_hash = Column(String, nullable=False)
     uploaded_by = Column(UUID(as_uuid=True), ForeignKey("users.id"), nullable=True)
     uploaded_at = Column(DateTime, default=datetime.utcnow)
+    team = Column(Enum(TeamSide, name="teamside"), nullable=False, default=TeamSide.red)
+    notes = Column(Text, nullable=True)
 
     # Relationships
     test = relationship("Test", back_populates="evidences")