Improve code quality - base class, exceptions, imports, tests

[cloudsmithy]

Summary

Code quality refactoring that reduces ~400 lines while fixing several bugs and improving maintainability.

Changes

Architecture

• Add BaseMilvusClient base class — eliminates duplicated __init__ + _get_client() across 10 client modules
• Add safe_int() utility — eliminates repeated null/string checking for row_count
• Remove duplicate OutputFormatter class from CliClient.py (was defined in both CliClient.py and OutputFormatter.py)

Bug Fixes

• show_loading_progress was returning hardcoded {"loading_progress": "100%"} — now calls real get_load_state API
• get_index_build_progress was returning hardcoded {"progress": "100%", "state": "Finished"} — now calls real describe_index API
• insert/upsert list-of-lists conversion had field misalignment when collection has auto_id — now correctly skips auto_id fields
• list_user_roles could return tuple instead of list — now always returns list
• CliClient.__init__ assigned self.formatter twice

Exception Handling

• Replace all 93 raise Exception(f"...{str(e)}") with raise RuntimeError/ValueError(f"...{e}") from e
• Fix all 26 bare except: → except Exception: (was catching KeyboardInterrupt)
• Use ConnectionError in BaseMilvusClient._get_client()
• Use ValueError for business logic validation (missing partition, user not found, etc.)

Import Cleanup

• Replace from .xxx import * with explicit side-effect imports in entry points
• Replace sys.path.append hack with relative imports in 7 script files
• Add try/except ImportError pattern for dual-mode compatibility (package import + direct run)
• Remove unused import sys / import os from 7 files

Housekeeping

• Remove stale Dockerfile.test (single line, unused)
• Remove .DS_Store from git tracking
• Add .cursor/, .kiro/, test.env to .gitignore
• Update README.md project structure to match actual filenames
• Remove test.env from repo (contained credentials)

Test Fixes

• Fix test_describe_database — assert correct API response key (name not database_name)
• Fix test_get_partition_stats — use _default partition to avoid ordering dependency
• Fix test_list_users — don't hardcode db_admin (Zilliz Cloud specific)
• Fix test_get_index_build_progress — match real API response format
• Handle auth errors gracefully in test_grant_and_revoke_privilege
• Fix all bare except: in test files

Stats

40 files changed, 496 insertions(+), 895 deletions(-)

Testing

102 unit tests passing against local Milvus standalone.

[nameczz]

@cloudsmithy Thanks for the PR! It looks great, but merging is currently blocked because your commits need verified signatures.
Could you please re-sign your commits or set up a GPG key to meet the Verified Signature requirement? Once that's done, we should be able to move forward. Thanks!