Reorganize folder structure and add XUnit test framework

[Copilot]

Reorganizes repository to follow F# project conventions with separate src/ and tests/ directories. Adds XUnit test infrastructure with initial domain type tests.

Changes

• Project structure: Moved all source files to src/WebmentionFs/, created tests/WebmentionFs.Tests/
• Solution file: Added WebmentionFs.slnx (XML format) with logical folder organization
• Test framework: XUnit on .NET 8.0 with project reference to main library (netstandard2.1)
• Initial tests: 4 unit tests covering core domain types (UrlData, EndpointUrlData, MentionTypes, Webmention)
• Documentation: Updated README with folder structure, build commands, and test instructions; updated test.fsx path reference

Structure

WebmentionFs/
├── src/WebmentionFs/              # Main library
│   ├── Domain.fs
│   ├── *Service.fs files
│   └── WebmentionFs.fsproj
├── tests/WebmentionFs.Tests/      # XUnit tests
│   ├── Tests.fs
│   └── WebmentionFs.Tests.fsproj
└── WebmentionFs.slnx              # Solution file

Build

dotnet build WebmentionFs.slnx     # Build all
dotnet test                         # Run tests

Original prompt

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This section details on the original issue you should resolve

<issue_title>Organize folder structure and add XUnit testing framework</issue_title>
<issue_description>## Organize Folder Structure and Add Testing Framework

To improve maintainability and follow best practices for F# /.NET projects, we should organize the folder structure as follows:

Proposed Folder Structure

• src/ — Contains the main project code
  • WebmentionFs/
    • Your F# source files (.fs)
    • Project file (WebmentionFs.fsproj)
• tests/ — Contains all tests
  • WebmentionFs.Tests/
    • XUnit-based test files (.fs)
    • Project file (WebmentionFs.Tests.fsproj)

Steps to Implement

1. **Move main logic into src/WebmentionFs/
2. Create a test project in tests/WebmentionFs.Tests/ using XUnit (the most common open-source .NET test framework).
   • Add XUnit NuGet package to the test project.
   • Ensure the test project references the main project.
   • Add example/unit tests for existing code.
3. (Optional) Solution File
   • If we add a solution, prefer SLNX
4. Update README with structure info and test running instructions.

References

• F# Project Layout Best Practices
• XUnit Documentation

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Deliverable: A well-organized folder structure and at least one XUnit-based test.

Labels: documentation, question</issue_description>

<agent_instructions>Make changes small and atomic. Make them self-contained. Test your changes. Commit early and often. Think deeply about your solution</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Organize folder structure and add XUnit testing framework #7

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[Copilot]

Pull request overview

Reorganizes the repository into standard src/ and tests/ layout and introduces an XUnit-based test project for the WebmentionFs library.

Changes:

• Moved library sources into src/WebmentionFs/ and created tests/WebmentionFs.Tests/ with XUnit on .NET 8.
• Added WebmentionFs.slnx solution for building/testing the whole repo.
• Updated README and test.fsx to reflect new structure and test commands.

Reviewed changes

Copilot reviewed 5 out of 14 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/WebmentionFs.Tests/WebmentionFs.Tests.fsproj	Adds XUnit test project referencing the main library.
tests/WebmentionFs.Tests/Tests.fs	Introduces initial unit tests for core domain types.
test.fsx	Updates referenced DLL path to match new src/ structure.
src/WebmentionFs/WebmentionValidationService.fs	Adds/relocates webmention content validation logic under src/.
src/WebmentionFs/WebmentionSenderService.fs	Adds/relocates sender service for endpoint delivery under src/.
src/WebmentionFs/WebmentionReceiverService.fs	Adds/relocates receiver service composing request + content validation.
src/WebmentionFs/WebmentionFs.fsproj	New project file under src/ with package metadata and compile includes.
src/WebmentionFs/Utils.fs	Adds/relocates shared HTTP/form/HTML helper utilities.
src/WebmentionFs/UrlDiscoveryService.fs	Adds/relocates endpoint discovery implementation under src/.
src/WebmentionFs/RequestValidationService.fs	Adds/relocates request validation logic and error handling.
src/WebmentionFs/Domain.fs	Adds/relocates core domain/result types.
src/WebmentionFs/Constants.fs	Adds/relocates constants (selectors, error messages, etc.).
WebmentionFs.slnx	Adds solution file organizing src and tests projects.
README.md	Documents new folder structure and build/test instructions.

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