Enhanced query endpoints with filtering and global artifacts/tags APIs (#18)

- Add search and tag filters to /api/v1/uploads endpoint
- Add sort/order parameters to /api/v1/uploads endpoint
- Add min_size/max_size filters to package artifacts endpoint
- Add sort/order parameters to package artifacts endpoint
- Add from/to date filters to tags endpoint
- Add global /api/v1/artifacts endpoint with project/package/tag/size/date filters
- Add global /api/v1/tags endpoint with project/package/search/date filters
- Add GlobalArtifactResponse and GlobalTagResponse schemas

backend/app/schemas.py

@@ -343,6 +343,44 @@ class PackageArtifactResponse(BaseModel):
         from_attributes = True
 
 
+class GlobalArtifactResponse(BaseModel):
+    """Artifact with project/package context for global listing"""
+
+    id: str
+    sha256: str
+    size: int
+    content_type: Optional[str]
+    original_name: Optional[str]
+    created_at: datetime
+    created_by: str
+    format_metadata: Optional[Dict[str, Any]] = None
+    ref_count: int = 0
+    # Context from tags/packages
+    projects: List[str] = []  # List of project names containing this artifact
+    packages: List[str] = []  # List of "project/package" paths
+    tags: List[str] = []  # List of "project/package:tag" references
+
+    class Config:
+        from_attributes = True
+
+
+class GlobalTagResponse(BaseModel):
+    """Tag with project/package context for global listing"""
+
+    id: UUID
+    name: str
+    artifact_id: str
+    created_at: datetime
+    created_by: str
+    project_name: str
+    package_name: str
+    artifact_size: Optional[int] = None
+    artifact_content_type: Optional[str] = None
+
+    class Config:
+        from_attributes = True
+
+
 # Upload response
 class UploadResponse(BaseModel):
     artifact_id: str