fix: 修复深色主题和仓库同步

[GaoMengGu]

变更

• 为 ComboBox 下拉项和设置页签选中态补充显式 WPF 主题模板，避免深色主题下套用系统白色选中态。
• 绝对仓库 URL 按 github.com/gitee.com 主机识别 provider，避免 provider 字段滞后导致 GitHub URL 被拒绝。
• Gitee archive 端点返回 400 或非 zip 时回退到 Gitee API 文件树下载，公开仓库无需 Token。
• 增加静态验证约束覆盖上述回归。

验证

• PASS: dotnet build src/PlugHub.Framework/PlugHub.Framework.csproj
• PASS: dotnet build src/PlugHub.Wpf/PlugHub.Wpf.csproj
• PASS: dotnet build src/PlugHub.StaticValidation/PlugHub.StaticValidation.csproj
• PASS: dotnet build src/PlugHub.Manager/PlugHub.Manager.csproj
• PASS: dotnet build src/PlugHub.Tests/PlugHub.Tests.csproj
• PASS: git diff --check
• BLOCKED: dotnet run --project src/PlugHub.StaticValidation/PlugHub.StaticValidation.csproj fails on this Ubuntu host because mono is not installed for net48 execution.

未做 Windows + Revit 2020 实机验证。