fix: more robust casting of int / float in grading policy

[nsprenkle]

Description

Better handles mistyped values in Grading Policies, as below:

{
    "str_of_float_which_should_be_int": "2.0",
    "str_of_float_which_should_be_float": "1.234",
    "str_of_int_which_should_be_int": "2",
    "float_which_should_be_int": 2.0,
    "int_which_should_be_int": 2,
    "float_which_should_be_float": 1.234
}

Previously, string representations of numbers would cause breakages. Blind casting to float or int caused issues where an int represented as a str formatted as a float would cause further casting issues.

Supporting information

Jira - https://2u-internal.atlassian.net/browse/AU-2934

Builds off of #273 , which added int casting of str, this further adds conversion of float represented as str (e.g. 2.0) for a value that should be an int.

Testing instructions

Load currently breaking progress page, verify fix causes page to work correctly.

Deadline

ASAP - Currently causing C2 learner issue.

[Copilot]

Pull request overview

This PR makes grading policy parsing in the Course Home Progress API more tolerant of numeric values that are incorrectly stored as strings (including float-formatted strings like "2.0"), preventing progress page breakages caused by type errors.

Changes:

• Added _to_float / _to_int helpers for resilient numeric casting of grading policy fields.
• Updated grading policy mapping to use these helpers for weight, drop_count, and min_count.
• Extended progress API aggregation tests with a scenario covering float-formatted string counts (e.g., "1.0" / "2.0").

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
lms/djangoapps/course_home_api/progress/api.py	Introduces tolerant numeric casting helpers and applies them when building the grading policy map.
lms/djangoapps/course_home_api/progress/tests/test_api.py	Adds/renames aggregation scenarios to cover string-int and string-float grading policy values.

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.