feat: render release Description blurb on Session, Mix, and Cut detail pages

New shared ReleaseDescription control renders the blurb in a uniform themed block
below the hero/header; null/whitespace renders nothing, with no layout artifact.

DeepDrftPublic.Client/Controls/ReleaseDescription.razor

@@ -0,0 +1,19 @@
+@namespace DeepDrftPublic.Client.Controls
+
+@* Shared presentational blurb block for release detail pages. Renders the release's short
+   Description paragraph in a uniform styled block placed just below the hero/header on every
+   medium (Session, Mix, Cut). Purely presentational — owns no data fetch and no player wiring.
+   A null/whitespace Description renders nothing at all: no block, no divider, no whitespace
+   artifact (the guard lives here so every consumer gets it for free). *@
+
+@if (!string.IsNullOrWhiteSpace(Description))
+{
+    <div class="deepdrft-release-description">
+        <p class="deepdrft-release-description-text">@Description</p>
+    </div>
+}
+
+@code {
+    /// <summary>The release's short description blurb. Null/whitespace renders nothing.</summary>
+    [Parameter] public string? Description { get; set; }
+}

DeepDrftPublic.Client/Pages/CutDetail.razor

@@ -115,6 +115,8 @@ else
             </div>
         </Header>
         <BodyContent>
+            @* Blurb sits between the header and the track-list divider. *@
+            <ReleaseDescription Description="@release.Description" />
             <MudDivider Class="cut-detail-divider" />
             @if (ViewModel.Tracks.Count == 0)
             {

DeepDrftPublic.Client/Pages/MixDetail.razor

@@ -85,6 +85,10 @@ else
                     </PlayContent>
                 </ReleaseHeroOverlay>
             </Hero>
+            <BodyContent>
+                @* Blurb sits below the hero, inside the scaffold's foreground stacking context. *@
+                <ReleaseDescription Description="@release.Description" />
+            </BodyContent>
         </ReleaseDetailScaffold>
       </MudContainer>
     </div>

DeepDrftPublic.Client/Pages/SessionDetail.razor

@@ -83,6 +83,8 @@ else
             </PlayContent>
         </ReleaseHeroOverlay>
 
+        <ReleaseDescription Description="@release.Description" />
+
     </MudContainer>
 }