lint(ruff): fix E402 and related import issues

- Fix E402 by removing sys.path hacks and ensuring imports are at module top level
- Replace ad-hoc imports with proper package imports (filter_plugins, lookup_plugins, module_utils, cli)
- Make lookup plugins importable via package paths (e.g. lookup_plugins.application_gid)
- Clean up test imports to rely on installed package layout instead of sys.path manipulation
- Partially fix F821 caused by missing/invalid imports

This establishes a consistent, ruff-compliant import architecture across CLI, filters, plugins, and tests.

build/lib/cli/setup/applications.py

@@ -3,17 +3,8 @@ import argparse
 import yaml
 import sys
 from pathlib import Path
-
-# Ensure project root on PYTHONPATH so module_utils is importable
-repo_root = Path(__file__).resolve().parent.parent.parent
-sys.path.insert(0, str(repo_root))
-
-# Add lookup_plugins for application_gid
-plugin_path = repo_root / "lookup_plugins"
-sys.path.insert(0, str(plugin_path))
-
 from module_utils.dict_renderer import DictRenderer
-from application_gid import LookupModule
+from lookup_plugins.application_gid import LookupModule
 
 def load_yaml_file(path: Path) -> dict:
     if not path.exists():