feat: add hide_zero_spend parameter to litellm_cost()

Adds optional hide_zero_spend parameter (default False) to filter out
models with bash.00 spend from the per-model breakdown. Useful when
free-tier or subscription models (e.g. Ollama Cloud) dominate the
breakdown with high token counts but zero cost.

- Updated litellm_cost() signature with hide_zero_spend parameter
- Added filtering logic in model line builder
- Added hidden model count summary line
- Updated README with parameter documentation
- Bumped version to 1.2.0

README.md

@@ -10,6 +10,11 @@ Check LiteLLM proxy health and authentication status. Returns which models are h
 ### `litellm_cost`
 Get LiteLLM cost breakdown for a date range. Returns per-model and per-day spend, token counts, cache hit rate, and request stats.
 
+**Parameters:**
+- `start_date` (str, required): Start date in YYYY-MM-DD format
+- `end_date` (str, required): End date in YYYY-MM-DD format
+- `hide_zero_spend` (bool, default false): Hide models with $0.00 spend. Useful when free-tier or subscription models (e.g. Ollama Cloud) dominate the breakdown with high token counts but zero cost.
+
 ### `litellm_history`
 Get recent LiteLLM request history. Returns the most recent N requests with model, call type, status, duration, token counts, cache hit %, and per-request cost. Useful for understanding which models are being called and how much individual requests cost.