feat: 7 Analyse-Module auf 100% — Backend-Endpoints, DB-Model, Frontend-Persistenz

Alle 7 Analyse-Module (Requirements → Report) von ~80% auf 100% gebracht:
- Modul 1 (Requirements): POST/DELETE Endpoints + Frontend-Anbindung + Rollback
- Modul 2 (Controls): Evidence-Linking UI mit Validity-Badge
- Modul 3 (Evidence): Pagination (Frontend + Backend)
- Modul 4 (Risk Matrix): Mitigation-UI, Residual Risk, Status-Workflow
- Modul 5 (AI Act): AISystemDB Model, 6 CRUD-Endpoints, Backend-Persistenz
- Modul 6 (Audit Checklist): PDF-Download + Session-History
- Modul 7 (Audit Report): Detail-Seite mit Checklist Sign-Off + Navigation

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend-compliance/compliance/db/models.py

@@ -401,6 +401,60 @@ class RiskDB(Base):
             return RiskLevelEnum.LOW
 
 
+class AIClassificationEnum(str, enum.Enum):
+    """AI Act risk classification."""
+    PROHIBITED = "prohibited"
+    HIGH_RISK = "high-risk"
+    LIMITED_RISK = "limited-risk"
+    MINIMAL_RISK = "minimal-risk"
+    UNCLASSIFIED = "unclassified"
+
+
+class AISystemStatusEnum(str, enum.Enum):
+    """Status of an AI system in compliance tracking."""
+    DRAFT = "draft"
+    CLASSIFIED = "classified"
+    COMPLIANT = "compliant"
+    NON_COMPLIANT = "non-compliant"
+
+
+class AISystemDB(Base):
+    """
+    AI System registry for AI Act compliance.
+    Tracks AI systems, their risk classification, and compliance status.
+    """
+    __tablename__ = 'compliance_ai_systems'
+
+    id = Column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
+    name = Column(String(300), nullable=False)
+    description = Column(Text)
+    purpose = Column(String(500))
+    sector = Column(String(100))
+
+    # AI Act classification
+    classification = Column(Enum(AIClassificationEnum), default=AIClassificationEnum.UNCLASSIFIED)
+    status = Column(Enum(AISystemStatusEnum), default=AISystemStatusEnum.DRAFT)
+
+    # Assessment
+    assessment_date = Column(DateTime)
+    assessment_result = Column(JSON)                                      # Full assessment result
+    obligations = Column(JSON)                                            # List of AI Act obligations
+    risk_factors = Column(JSON)                                           # Risk factors from assessment
+    recommendations = Column(JSON)                                        # Recommendations from assessment
+
+    # Timestamps
+    created_at = Column(DateTime, default=datetime.utcnow)
+    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+
+    __table_args__ = (
+        Index('ix_ai_system_classification', 'classification'),
+        Index('ix_ai_system_status', 'status'),
+    )
+
+    def __repr__(self):
+        return f"<AISystem {self.name} ({self.classification.value})>"
+
+
 class AuditExportDB(Base):
     """
     Tracks audit export packages generated for external auditors.