fix: add security checks and tests for code review

Security:
- Add authorization checks to list_packages, update_package, delete_package endpoints
- Add MAX_TOTAL_ARTIFACTS limit (1000) to prevent memory exhaustion during dependency resolution
- Add TooManyArtifactsError exception for proper error handling

UI:
- Display reverse dependency errors in PackagePage
- Add warning display for failed dependency fetches in DependencyGraph

Tests:
- Add unit tests for metadata extraction (deb, wheel, tarball, jar)
- Add unit tests for rate limit configuration
- Add unit tests for PyPI registry client

backend/app/dependencies.py

@@ -109,9 +109,17 @@ class DependencyDepthExceededError(DependencyError):
         super().__init__(f"Dependency resolution exceeded maximum depth of {max_depth}")
 
 
+class TooManyArtifactsError(DependencyError):
+    """Raised when dependency resolution resolves too many artifacts."""
+    def __init__(self, max_artifacts: int):
+        self.max_artifacts = max_artifacts
+        super().__init__(f"Dependency resolution exceeded maximum of {max_artifacts} artifacts")
+
+
 # Safety limits to prevent DoS attacks
 MAX_DEPENDENCY_DEPTH = 100  # Maximum levels of nested dependencies
 MAX_DEPENDENCIES_PER_ARTIFACT = 200  # Maximum direct dependencies per artifact
+MAX_TOTAL_ARTIFACTS = 1000  # Maximum total artifacts in resolution to prevent memory issues
 
 
 def parse_ensure_file(content: bytes) -> EnsureFileContent:
@@ -849,6 +857,10 @@ def resolve_dependencies(
         visited.add(artifact_id)
         resolution_path_sync.pop()
 
+        # Check total artifacts limit
+        if len(resolution_order) >= MAX_TOTAL_ARTIFACTS:
+            raise TooManyArtifactsError(MAX_TOTAL_ARTIFACTS)
+
         # Add to resolution order (dependencies before dependents)
         resolution_order.append(artifact_id)
 
@@ -1257,6 +1269,10 @@ async def resolve_dependencies_with_fetch(
         visited.add(artifact_id)
         resolution_path.pop()
 
+        # Check total artifacts limit
+        if len(resolution_order) >= MAX_TOTAL_ARTIFACTS:
+            raise TooManyArtifactsError(MAX_TOTAL_ARTIFACTS)
+
         resolution_order.append(artifact_id)
 
         resolved_artifacts[artifact_id] = ResolvedArtifact(