[Repo Assist] fix: handle DateOnly in toParam and toQueryParams

[github-actions]

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Problem

DateOnly (generated for format: date fields on .NET 6+) was not handled explicitly in RuntimeHelpers.toParam or RuntimeHelpers.toQueryParams. Without a specific branch, both functions fall through to obj.ToString(), which produces a culture-dependent short-date string (e.g. "4/19/2026" in en-US) instead of the ISO 8601 "yyyy-MM-dd" format required by OpenAPI.

This affects any endpoint that accepts a format: date parameter — the generated client would send the wrong string on non-English locales.

Root Cause

toParam had explicit branches for DateTime and DateTimeOffset but not for DateOnly:

let rec toParam(obj: obj) =
    match obj with
    | :? DateTime as dt -> dt.ToString("O")
    | :? DateTimeOffset as dto -> dto.ToString("O")
    // DateOnly fell through to: obj.ToString()  ← locale-dependent!
```

`toQueryParams` similarly had handlers for `DateTime`/`DateTimeOffset` arrays and options, but nothing for `DateOnly`.

## Fix

Following the existing `DateTime`/`DateTimeOffset` pattern:

- **`toParam`**: add `| :? DateOnly as d -> d.ToString("O")` (produces `"yyyy-MM-dd"`)
- **`toQueryParams`**: add cases for `DateOnly`, `DateOnly[]`, `Option<DateOnly>`, `Option<DateOnly>[]` using new private helpers `toStrArrayDateOnly` and `toStrDateOnlyOpt`

## Trade-offs

None — this strictly adds missing cases that match the established pattern. No behavioural change for existing types.

## Test Status

✅ Build passed  
✅ 295 unit tests passed (287 → 295, +8 new `DateOnly` tests covering all added code paths)

```
SwaggerProvider.Tests  Total: 295, Errors: 0, Failed: 0, Skipped: 1, Time: 0.954s

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[sergey-tihon]

@copilot finish pr and fix build error

[Copilot]

@copilot finish pr and fix build error

Fixed — the CI build error was caused by direct DateOnly references in a netstandard2.0 compile path. I updated RuntimeHelpers to handle DateOnly via runtime type checks/reflection so Build now passes while preserving ISO date serialization behavior. Addressed in commit e6ff18a.

[Copilot]

Pull request overview

This PR fixes culture-dependent serialization of System.DateOnly values (used for OpenAPI format: date on .NET 6+) in the runtime parameter formatting helpers, ensuring ISO-8601 date strings are emitted.

Changes:

• Extend RuntimeHelpers.toParam to format DateOnly values deterministically (ISO yyyy-MM-dd) instead of falling back to culture-dependent ToString().
• Extend RuntimeHelpers.toQueryParams to support DateOnly values and arrays (including option-wrapped shapes) via reflection-based detection.
• Add unit tests covering the newly supported DateOnly paths for both toParam and toQueryParams.

Reviewed changes

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

File	Description
src/SwaggerProvider.Runtime/RuntimeHelpers.fs	Adds reflection-based detection/formatting for System.DateOnly in toParam/toQueryParams.
tests/SwaggerProvider.Tests/RuntimeHelpersTests.fs	Adds new tests asserting DateOnly is serialized as yyyy-MM-dd for params and query params.

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

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