Chore/deps and docs

[DecSmith42]

This pull request makes several documentation and configuration improvements to the Atom repository. The most significant changes are the introduction of new, clearer agent instructions, updates to the documentation for consistency and accuracy, and enhancements to the DocFX documentation site including theming and resource inclusion.

Documentation and Guidance Improvements:

• Replaces .github/copilot-instructions.md with a new AGENTS.md file, providing clearer, more concise, and up-to-date guidance for AI agents and contributors, including repository structure, conventions, and checklists. [1] [2]
• Updates README.md to clarify requirements, recommend the global atom tool, and improve setup instructions. [1] [2]

DocFX Documentation Site Enhancements:

• Updates docfx.json to include the API table of contents, add the project license to resources, set a custom logo, and apply the local docfx-theme for a more branded documentation experience. [1] [2] [3] [4]
• Adds a CSS rule for the documentation logo to improve its appearance on the site.

Technical Documentation Consistency:

• Refines build definition documentation to recommend interface-based builds, clarifies when to use partial classes, and updates examples for greater accuracy and clarity. [1] [2] [3]
• Updates source generator and testing documentation to match the new build definition guidance and provide more accurate test examples. [1] [2] [3]
• Clarifies workflow generation requirements and build/test conventions in the relevant documentation.

These changes improve onboarding, maintenance, and the user experience for both contributors and consumers of the Atom project.

[Copilot]

Pull request overview

This PR updates Atom’s contributor/agent guidance and documentation while also bumping several NuGet dependencies and refining the DocFX site configuration/assets.

Changes:

• Replace the previous Copilot instructions with a new AGENTS.md and update multiple docs pages for consistency around interface-based builds and CLI usage.
• Update DocFX site inputs/resources and add a local styling override for the logo.
• Bump several package references across projects/tests (e.g., Verify.NUnit, Invex.* packages, PublicApiAnalyzers).

Reviewed changes

Copilot reviewed 33 out of 33 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
toc.yml	Adjusts main DocFX TOC wiring to reference the API TOC.
docfx.json	Expands DocFX content/resources and attempts to apply a local theme.
docfx-theme/public/main.css	Adds CSS to standardize the DocFX logo sizing/appearance.
index.md	Replaces redirecting landing page with a “Start here” content page.
README.md	Clarifies .NET 10 requirement, global tool usage, and dotnet run --project _atom invocation.
global.json	Introduces SDK pinning for consistent .NET builds.
AGENTS.md	Adds new agent/contributor guidance and repo conventions/checklists.
.github/copilot-instructions.md	Removes the previous instructions file (replaced by AGENTS.md).
docs/reference/cli.md	Updates CLI docs (invocation patterns, discovery behavior, flags, and secret-handling guidance).
docs/workflows/overview.md	Updates workflow documentation to match interface-based build guidance.
docs/getting-started/introduction.md	Updates conceptual definitions to reflect interface-based builds as recommended.
docs/getting-started/your-first-build.md	Updates quickstart examples to current package naming and recommended build patterns.
docs/getting-started/base-vs-workflow-build.md	Updates guidance/examples for interface vs partial-class builds and workflow builds.
docs/core-concepts/build-definitions.md	Reworks build-definition documentation around interface-first guidance and alternatives.
docs/built-in-targets/generate-workflow-files.md	Clarifies requirements for workflow generation for interface vs partial-class builds.
docs/developer-guide/source-generators.md	Updates generator documentation to cover interface and partial-class build definitions.
docs/developer-guide/testing.md	Updates developer testing guidance and provides a concrete “build model” test example.
docs/developer-guide/writing-a-module.md	Updates module-writing docs to the current Invex.Atom.Build major version guidance.
docs/filterConfig.yml	Updates DocFX API filtering patterns to match Invex.* namespaces.
tests/Invex.Atom.Build.Tests/Invex.Atom.Build.Tests.csproj	Bumps Verify.NUnit test dependency.
tests/Invex.Atom.Build.SourceGenerators.Tests/Invex.Atom.Build.SourceGenerators.Tests.csproj	Bumps Verify.NUnit test dependency.
tests/Invex.Atom.Module.DevopsWorkflows.Tests/Invex.Atom.Module.DevopsWorkflows.Tests.csproj	Bumps Verify.NUnit test dependency.
tests/Invex.Atom.Module.GithubWorkflows.Tests/Invex.Atom.Module.GithubWorkflows.Tests.csproj	Bumps Verify.NUnit test dependency.
tests/Invex.Atom.Tool.Tests/Invex.Atom.Tool.Tests.csproj	Bumps Verify.NUnit test dependency.
tests/Invex.Atom.Workflows.Tests/Invex.Atom.Workflows.Tests.csproj	Bumps Verify.NUnit test dependency.
src/Invex.Atom.Build/Invex.Atom.Build.csproj	Bumps Invex.* runtime deps and PublicApiAnalyzers.
src/Invex.Atom.Workflows/Invex.Atom.Workflows.csproj	Bumps Invex.StructuredText and PublicApiAnalyzers.
src/Invex.Atom.Module.AzureKeyVault/Invex.Atom.Module.AzureKeyVault.csproj	Bumps PublicApiAnalyzers.
src/Invex.Atom.Module.AzureStorage/Invex.Atom.Module.AzureStorage.csproj	Bumps PublicApiAnalyzers.
src/Invex.Atom.Module.DevopsWorkflows/Invex.Atom.Module.DevopsWorkflows.csproj	Bumps StructuredText.AzureDevopsPipelines and PublicApiAnalyzers.
src/Invex.Atom.Module.Dotnet/Invex.Atom.Module.Dotnet.csproj	Bumps PublicApiAnalyzers.
src/Invex.Atom.Module.GithubWorkflows/Invex.Atom.Module.GithubWorkflows.csproj	Bumps StructuredText.GithubActions and PublicApiAnalyzers.
src/Invex.Atom.Module.GitVersion/Invex.Atom.Module.GitVersion.csproj	Bumps PublicApiAnalyzers.