Changes the API from opt-in hiding (hide_zero_spend) to opt-in showing
(show_zero_spend). Default behavior now hides sub-bash.001 models and
shows the summary line — cleaner for the common case where free-tier
models dominate the breakdown.
- Renamed parameter: hide_zero_spend → show_zero_spend
- Inverted logic: default False means hide by default
- Updated docstrings, README, ARCHITECTURE.md
- ARCHITECTURE.md: Added natural language date resolution section,
hide_zero_spend parameter docs, updated example output, changelog
- README.md: Added changelog section with v1.2.0 and v1.1.0 entries
- Updated version metadata and creation date
- README: three functions, litellm_history params and cost awareness note
- ARCHITECTURE: full Function 3 section with endpoint, fields, output format,
token display rules, error paths, and performance considerations