[Animal] Add Warning for Milk Production Reduction

[allisterakun]

Adds a summary warning in HerdManager.formulate_rations() when any cows have had their milk production reduced due to ration formulation failure, reporting the number of affected animals and the average reduction in kg.

Context

Issue(s) closed by this pull request: closes #1874.

What

• Added a milk production reduction warning at the end of formulate_rations() in herd_manager.py. After all pens have been reformulated, the method checks if any cows have a milk_production_reduction > 0. If so, it logs a warning via OutputManager.add_warning() with the number of affected animals, the average reduction amount (in kg, formatted to 2 decimal places), and the simulation day.

Why

When a ration cannot be formulated for a cow, the model reduces the cow's milk production to lower nutrient requirements and make formulation feasible. While the reduction amount is collected in the output variables, this was not immediately evident to the user during the simulation. Adding a once-per-ration-formulation-interval warning alerts users that milk production has been reduced, how many animals were affected, and by how much on average, making the behavior transparent without requiring the user to inspect output variables.

How

At the end of formulate_rations(), after all pens have been reformulated, a list comprehension filters self.cows for any cow with milk_production.milk_production_reduction > 0. If the list is non-empty, the average reduction is computed and a warning is logged via self.om.add_warning(). This runs once per ration formulation interval call, summarizing all affected cows in a single warning rather than emitting per-animal warnings.

Test plan

Input Changes

• N/A

Output Changes

• N/A

Filter

[github-actions]

Current Coverage: 99%

Mypy errors on milk_production_reduction_warnings branch: 1144
Mypy errors on dev branch: 1144
No difference in error counts

[github-actions]

🚨 Please update the changelog. This PR cannot be merged until changelog.md is updated.

[github-actions]

Current Coverage: %

Mypy errors on milk_production_reduction_warnings branch: 1144
Mypy errors on dev branch: 1144
No difference in error counts

[github-actions]

🚨 Some tests have failed.

[github-actions]

Current Coverage: 99%

Mypy errors on milk_production_reduction_warnings branch: 1144
Mypy errors on dev branch: 1144
No difference in error counts