[Hotfix Main]: [FXC-5592] Results model for (TimeAveraging)ForceDistributionOutput

[github-actions]

Hotfix of PR #1817 (#1817) to the main branch.
Hey @piotrkluba, please review this hotfix PR created from your original PR.

⚠️ Note: This PR had conflicts with the base branch and was resolved automatically. Please review the changes carefully.

---

Note

Medium Risk
Touches core results discovery/downloading and parsing logic, so regressions could affect existing monitor/UDD/custom-force result access and downloads.

Overview
Adds first-class support for ForceDistributionOutput/TimeAverageForceDistributionOutput results: introduces a generic NamedResultsCollectionModel and migrates MonitorsResultModel, UserDefinedDynamicsResultModel, and CustomForceResultModel to use it, while adding a new ForceDistributionsResultModel that discovers *_forceDistribution.csv files and exposes per-output access + bulk download.

Extends Case/SimulationParams and the case results downloader to detect and optionally download these force-distribution results, adds parsing for both incremental and cumulative force/moment distributions (new output field constants, normal_direction axis, and CustomForceDistributionResultCSVModel), and adds validation/tests to reserve the names X_slicing/Y_slicing plus new test fixtures/mocked API responses for the new result files.

^{Written by Cursor Bugbot for commit a6cc3c8. This will update automatically on new commits. Configure here.}

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{Bugbot Autofix is OFF. To automatically fix reported issues with Cloud Agents, enable Autofix in the Cursor dashboard.}

[cursor]

Vacuous truth silently defaults to cumulative on empty data

Low Severity

In CustomForceDistributionResultCSVModel._preprocess, when self._values is falsy (e.g., None or empty dict {}), headers becomes an empty set. Python's all() on an empty iterable returns True (vacuous truth), so the method silently classifies the data as cumulative and sets _variables and _filter_when_zero to cumulative values without any actual evidence from the data. This bypasses the Flow360NotImplementedError that the else branch is designed to raise for unrecognized data, potentially masking issues during debugging.