parse_spec_str(), parse_specs_str(), order_tags(), and __repr__ are pure
text processing without test coverage, shared by the dpkg and rpm package
manager backends.
Add unit tests for valid and invalid spec strings, multi-line input with
and without a trailing newline, tag ordering with default values, and the
repr layout.
Signed-off-by: Jan Lindemann <jan@janware.com>
Assisted-by: unsloth/Qwen3.8-27B-GGUF:Q4_K_M with pi.dev v0.85.1
