fix: make drop match only the named path

[rodboev]

/drop was using substring matching for non-glob paths. That made a command like /drop api\chat\route.ts remove both api\chat\route.ts and app\api\chat\route.ts when both files were in chat.

This keeps bare /drop and explicit glob behavior intact, but makes non-glob editable and read-only drops use exact path identity instead of substring containment.

Closes #4176

The duplicate-path reproduction from emincangencer's comment shaped the editable and read-only regression tests.

Validation:

• rtk python -m pytest tests/basic/test_commands.py -k cmd_drop -v
  • 6 passed, 67 deselected (run with TEMP/TMP/TMPDIR=D:\Repos\tmp)
• rtk python -m pytest tests/basic/test_commands.py::TestCommands::test_cmd_add_drop_directory tests/basic/test_commands.py::TestCommands::test_cmd_read_only_with_square_brackets -v
  • 2 passed
• rtk pre-commit run --all-files
  • isort, black, flake8, and codespell all passed