Modernize project, build, and tooling

[Avasam]

Modernize project, build, and tooling

Project / Solution / Build

• Convert to SDK-style .csproj
• Enable UseWindowsForms; drop legacy ClickOnce/bootstrapper cruft and explicit Compile/EmbeddedResource items (SDK globbing).
• Vendor the LiveSplit reference assemblies (LiveSplit.exe, LiveSplit.Core.dll, UpdateManager.dll) under lib/ with Private=false, replacing hardcoded absolute HintPaths.
  • Added lib/README.md with refresh instructions (pinned to LiveSplit 1.8.37).
• Dropped .sln entirely (single-project repo builds fine from the .csproj under both VS 2022 and the dotnet CLI).
• No lock files. Project too simple for 1 dependency that is already implicit.

Distribution / Versioning / Auto-updater

• Generate assembly metadata from csproj properties; removes Properties/AssemblyInfo.cs.
• Update changelog entries.
• Ship the plugin via GitHub Releases instead of committing the built DLL to source
• Ship a full PDB (DebugType=full) alongside the DLL for readable crash-report line numbers.
• Version now comes from the git tag: CI builds with -p:Version=<tag>, so AssemblyVersion/FileVersion and the factory's runtime Version match with no source edit. csproj <Version> (0.0.0-dev) is only a local-build fallback.

CI / tooling

• Add GitHub Actions CI workflow (windows-2022, .NET SDK 10, build + dotnet format check, upload DLL artifact).
• Added an automated Release publishing workflow with manifest / changelog validation.
• Apply shared configs (.editorconfig, .vscode/), remove custom .gitattributes overrides, and trim .gitignore from ~248 lines of boilerplate to project-relevant entries.

Docs

• Completely revamped the README
• Added contributing guidelines, Compiling and Publishing to CONTRIBUTING.md
• Added some Coding Agents guidance

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LLM/Coding agent used back-and-forth to massively speed up the process and analyze through the cruft. Leaving as draft until I properly finish reviewing all the text changes and "humanize" PR description in my own words. Code and config changes already fully human reviewed.