Add Add per-channel constraints parameters to OptimizationGrid.optimize(...)`.

PiperOrigin-RevId: 740470489

Author: viktoriias

CHANGELOG.md

@@ -37,6 +37,8 @@ To release a new version (e.g. from `1.0.0` -> `2.0.0`):
 * Add channel contribution area chart and channel contribution bump chart to
   model results summary report in the summarizer.
 * Add an extra check for zeros or negative values in `revenue_per_kpi`.
+* Add Add per-channel constraints parameters to
+ `OptimizationGrid.optimize(...)`.
 
 ## [1.0.7] - 2025-03-19