fix: Add cloud storage test dependencies and proper skipping (Kimi's issues #2 & #3)

Fixed cloud storage test failures and missing test dependencies:

Issue #2: Cloud Storage Test Failures (16 tests)
- Added availability checks for boto3, google-cloud-storage, azure-storage-blob
- Added @pytest.mark.skipif decorators to all 16 cloud storage tests
- Tests now skip gracefully when dependencies not installed
- Result: 4 passed, 16 skipped (instead of 16 failed)

Issue #3: Missing Test Dependencies
Added to [dependency-groups] dev:
- boto3>=1.26.0 (AWS S3 testing)
- google-cloud-storage>=2.10.0 (Google Cloud Storage testing)
- azure-storage-blob>=12.17.0 (Azure Blob Storage testing)
- psutil>=5.9.0 (process utilities)
- numpy>=1.24.0 (numerical operations)
- starlette>=0.31.0 (HTTP transport testing)
- httpx>=0.24.0 (HTTP client)

Test Results:
- Before: 16 failed (AttributeError on missing modules)
- After: 4 passed, 16 skipped (clean skip with reason)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

pyproject.toml

@@ -294,10 +294,24 @@ check_untyped_defs = false
 
 [dependency-groups]
 dev = [
+    # Core testing
     "pytest>=8.4.2",
     "pytest-asyncio>=0.24.0",
     "pytest-cov>=7.0.0",
     "coverage>=7.11.0",
+
+    # Code quality
     "ruff>=0.14.13",
     "mypy>=1.19.1",
+
+    # Test dependencies (Kimi's finding #3)
+    "psutil>=5.9.0",        # Process utilities for testing
+    "numpy>=1.24.0",        # Numerical operations
+    "starlette>=0.31.0",    # HTTP transport testing
+    "httpx>=0.24.0",        # HTTP client for testing
+
+    # Cloud storage testing (Kimi's finding #2)
+    "boto3>=1.26.0",                    # AWS S3
+    "google-cloud-storage>=2.10.0",     # Google Cloud Storage
+    "azure-storage-blob>=12.17.0",      # Azure Blob Storage
 ]