refactor: modularize Beam into new projects and interfaces

- Introduced modularity by splitting Beam into new projects: Beam.Abstractions, Beam.Models, and Beam.Downloaders.
- Refactored existing classes into appropriate namespaces and projects.
- Replaced specific implementations with abstractions (e.g., SourceLinkBuilder to LinkBuilder, State to IState, etc.).
- Updated interfaces: added ITemplate, IArticleData, IDownloadReport, and others for improved extensibility.
- Removed deprecated classes like SourceLinkBuilder and StateChangerFactory.
- Enhanced link handling in downloaders by refactoring to use `string` over `SourceLink`.
- Consolidated shared logic under Beam.Abstractions.

aeqw89.Beam/aeqw89.Beam.csproj

@@ -62,10 +62,22 @@
             <PackagePath>lib\$(TargetFramework)\</PackagePath>
             <Pack>true</Pack>
         </Content>
+        <Content Include="..\Beam.Fluent\bin\$(Configuration)\$(TargetFramework)\Beam.Fluent.dll">
+            <PackagePath>lib\$(TargetFramework)</PackagePath>
+            <Pack>true</Pack>
+        </Content>
+        <Content Include="..\Beam.Models\bin\$(Configuration)\$(TargetFramework)\Beam.Models.dll">
+            <PackagePath>lib\$(TargetFramework)</PackagePath>
+            <Pack>true</Pack>
+        </Content>
         <Content Include="..\Beam.Temporary.Cli\bin\$(Configuration)\$(TargetFramework)\HtmlAgilityPack.dll">
             <PackagePath>lib\$(TargetFramework)\</PackagePath>
             <Pack>true</Pack>
         </Content>
+        <Content Include="..\Beam.Api\bin\$(Configuration)\$(TargetFramework)\Beam.Api.dll">
+            <PackagePath>lib\$(TargetFramework)</PackagePath>
+            <Pack>true</Pack>
+        </Content>
         <PackageReference Include="HtmlAgilityPack" Version="1.11.72">
             <PrivateAssets />
             <Transitive>true</Transitive>
@@ -84,7 +96,7 @@
         </PackageReference>
     </ItemGroup>
     <ItemGroup>
-        <PackageReference Include="aeqw89.PersistentData" Version="1.1.0">
+        <PackageReference Include="aeqw89.PersistentData" Version="1.3.3">
             <PrivateAssets />
             <Transitive>true</Transitive>
         </PackageReference>