fix: apply pre-commit formatting fixes for 0.4.0 branch code

[Copilot]

The pre-commit CI job on the 0.4.0 branch was failing because new code introduced in that branch had formatting violations detected by ruff, ruff-format, mdformat, and several other hooks — causing a non-empty diff and exit code 1.

Changes

• ruff-format: Reformatted several files to comply with 88-char line length (multi-arg function calls split onto separate lines)
• ruff lint:
  • F401: Removed unused imports (pytest, os, Result) in test files
  • F841: Removed unused variable target in test_60_integration_stream.py
  • I001: Fixed import ordering across multiple test and source files
  • E402: Added # noqa: E402 to the late module-level imports in server_cache_and_stream.py; moved cads_mars_server imports above pytestmark in test_70_ws_integration.py
• mdformat: Reformatted k8s/DESIGN.md
• Misc: Fixed trailing whitespace, missing EOF newline (k8s/DESIGN.md, .gitignore), and TOML formatting (pyproject.toml)

The notable manual fix was in server_cache_and_stream.py, where late imports (after function definitions) required explicit suppression:

# Before — combined import, no noqa, E402 reported on subsequent blocks
from .config import (
    CACHE_FOLDER as _cfg_cache_folder,
    SHARED_ROOT as _cfg_shared_root,
    SHARES as _cfg_shares,
)

# After — ruff isort splits these; each needs its own noqa
from .config import (  # noqa: E402
    CACHE_FOLDER as _cfg_cache_folder,
)
from .config import (  # noqa: E402
    SHARED_ROOT as _cfg_shared_root,
)
from .config import (  # noqa: E402
    SHARES as _cfg_shares,
)
from .server import tidy  # noqa: E402

[gbiavati]

Formatting changes are always welcome if they make tests not fail