Stop embedding sources/PDB in shipped WASM assemblies

Set EmbedAllSources=false and DebugType=portable in the root
Directory.Build.props so the demo and API-reference assemblies no longer
carry an embedded PDB containing full source. The embedded source is
deflate-compressed, so Brotli cannot reclaim it - it was inflating
RadzenBlazorDemos.wasm from ~1.3MB to ~4.2MB Brotli (and the lazy API
bundle similarly).

The packable Radzen.Blazor library is unaffected: it is governed by
Radzen.Blazor/Directory.Build.props and still ships embedded sources in
its .snupkg for consumer step-into-source debugging.

Directory.Build.props

@@ -47,21 +47,11 @@
     <!-- Enable deterministic builds in CI/CD -->
     <ContinuousIntegrationBuild Condition="'$(CI)' == 'true'">true</ContinuousIntegrationBuild>
     
-    <!-- Embed source files for better debugging -->
+    <!-- Apps/tests/tools ship the DLL itself; embedded source can't be Brotli-recompressed and bloats the
-    <EmbedAllSources>true</EmbedAllSources>
+         shipped .wasm (~3.5 MB on RadzenBlazorDemos). Portable PDBs aid local debugging but are not published
-    <!--
+         in a Release Blazor WASM build. snupkg source-embedding lives in Radzen.Blazor/Directory.Build.props. -->
-      IMPORTANT:
+    <EmbedAllSources>false</EmbedAllSources>
-      - NuGet symbol packages (.snupkg) require portable PDB files.
+    <DebugType>portable</DebugType>
-      - If DebugType=embedded, there are no standalone PDBs, so the .snupkg ends up effectively empty.
-      Use portable PDBs when symbols are enabled; otherwise use embedded for local debugging convenience.
-    -->
-    <!--
-      NOTE: Directory.Build.props is imported before project files, so properties like IncludeSymbols
-      set in a .csproj may not be available yet for Conditions here.
-      IsPacking *is* set by `dotnet pack`, so use that to switch DebugType for symbol packages.
-    -->
-    <DebugType Condition="'$(IsPacking)' == 'true'">portable</DebugType>
-    <DebugType Condition="'$(IsPacking)' != 'true'">embedded</DebugType>
   </PropertyGroup>
 
   <PropertyGroup Label="Demos and Tests Project Configuration" Condition="$(MSBuildProjectName.Contains('Demos')) OR $(MSBuildProjectName.Contains('Tests'))">

Radzen.Blazor/Directory.Build.props

@@ -47,7 +47,8 @@
     <!-- Enable deterministic builds in CI/CD -->
     <ContinuousIntegrationBuild Condition="'$(CI)' == 'true'">true</ContinuousIntegrationBuild>
     
-    <!-- Embed source files for better debugging -->
+    <!-- Packable library only: embeds source into the .snupkg portable PDB for consumer step-into-source.
+         App projects override this to false in the root Directory.Build.props - do not re-sync that here. -->
     <EmbedAllSources>true</EmbedAllSources>
     <!--
       IMPORTANT: