Add audit log and history API endpoints (#20)

- Add audit log endpoints: GET /api/v1/audit-logs with filters, project-scoped, package-scoped
- Add upload history endpoints: package uploads, artifact uploads
- Add artifact provenance endpoint: GET /api/v1/artifact/{id}/history
- Add audit logging for project.create, package.create, tag.create, tag.update
- Add AuditLogResponse, UploadHistoryResponse, ArtifactProvenanceResponse schemas
- Add 18 integration tests for new endpoints

backend/app/schemas.py

@@ -189,6 +189,93 @@ class TagHistoryResponse(BaseModel):
         from_attributes = True
 
 
+class TagHistoryDetailResponse(BaseModel):
+    """Tag history with artifact metadata for each version"""
+
+    id: UUID
+    tag_id: UUID
+    tag_name: str
+    old_artifact_id: Optional[str]
+    new_artifact_id: str
+    changed_at: datetime
+    changed_by: str
+    # Artifact metadata for new artifact
+    artifact_size: int
+    artifact_original_name: Optional[str]
+    artifact_content_type: Optional[str]
+
+    class Config:
+        from_attributes = True
+
+
+# Audit log schemas
+class AuditLogResponse(BaseModel):
+    """Audit log entry response"""
+
+    id: UUID
+    action: str
+    resource: str
+    user_id: str
+    details: Optional[Dict[str, Any]]
+    timestamp: datetime
+    source_ip: Optional[str]
+
+    class Config:
+        from_attributes = True
+
+
+# Upload history schemas
+class UploadHistoryResponse(BaseModel):
+    """Upload event with artifact details"""
+
+    id: UUID
+    artifact_id: str
+    package_id: UUID
+    package_name: str
+    project_name: str
+    original_name: Optional[str]
+    tag_name: Optional[str]
+    uploaded_at: datetime
+    uploaded_by: str
+    source_ip: Optional[str]
+    deduplicated: bool
+    # Artifact metadata
+    artifact_size: int
+    artifact_content_type: Optional[str]
+
+    class Config:
+        from_attributes = True
+
+
+# Artifact provenance schemas
+class ArtifactProvenanceResponse(BaseModel):
+    """Full provenance/history of an artifact"""
+
+    artifact_id: str
+    sha256: str
+    size: int
+    content_type: Optional[str]
+    original_name: Optional[str]
+    created_at: datetime
+    created_by: str
+    ref_count: int
+    # First upload info
+    first_uploaded_at: datetime
+    first_uploaded_by: str
+    # Usage statistics
+    upload_count: int
+    # References
+    packages: List[Dict[str, Any]]  # List of {project_name, package_name, tag_names}
+    tags: List[
+        Dict[str, Any]
+    ]  # List of {project_name, package_name, tag_name, created_at}
+    # Upload history
+    uploads: List[Dict[str, Any]]  # List of upload events
+
+    class Config:
+        from_attributes = True
+
+
 class ArtifactTagInfo(BaseModel):
     """Tag info for embedding in artifact responses"""