CMS Phase 9 Wave 3: Release Archive tab, medium selector, Session/Mix browsers

Renames Genre tab to Release Archive with switch-free medium card group
(Enum.GetValues-driven). Adds MediumFields single dispatch + CutFields/SessionFields/
MixFields per-medium sections embedded by all five upload/edit forms. BatchUpload
enforces single-track invariant for Session/Mix. Adds CmsSessionBrowser (hero-image
upload) and CmsMixBrowser (waveform status + per-row Generate trigger).
ICmsReleaseService/CmsReleaseService wraps api/release endpoints.
Note: medium selector is forward-compat only — API write path pending.

DeepDrftManager/Components/Pages/Tracks/ReleaseArchiveBrowser.razor

@@ -0,0 +1,37 @@
+@using DeepDrftModels.Enums
+@inject NavigationManager Navigation
+
+@* Release Archive: one card per ReleaseMedium, driven off Enum.GetValues + a display-metadata table.
+   No hardcoded three-arm switch in markup — adding a medium surfaces a new card automatically and only
+   needs one new entry in MediumCards below. Card idiom mirrors CmsGenreBrowser (MudCard + swatch). *@
+<MudGrid Spacing="3" Class="mt-2">
+    @foreach (var medium in Enum.GetValues<ReleaseMedium>())
+    {
+        var info = MediumCards[medium];
+        <MudItem xs="12" sm="6" md="4">
+            <MudCard Elevation="1"
+                     Style="cursor: pointer;"
+                     @onclick="@(() => Navigation.NavigateTo(info.Route))">
+                <div class="@($"cms-medium-swatch cms-medium-swatch--{info.SwatchModifier}")"></div>
+                <MudCardContent>
+                    <MudText Typo="Typo.h6">@info.Label</MudText>
+                    <MudText Typo="Typo.body2" Class="mud-text-secondary">@info.Descriptor</MudText>
+                </MudCardContent>
+            </MudCard>
+        </MudItem>
+    }
+</MudGrid>
+
+@code {
+    private sealed record MediumCardInfo(string Label, string Descriptor, string SwatchModifier, string Route);
+
+    // The one place medium → display + navigation target lives. A future medium adds one entry here;
+    // the markup above is untouched. The enum→record dictionary is a switch, data-structured (§3.1).
+    private static readonly IReadOnlyDictionary<ReleaseMedium, MediumCardInfo> MediumCards =
+        new Dictionary<ReleaseMedium, MediumCardInfo>
+        {
+            [ReleaseMedium.Cut] = new("Cuts", "Studio singles, EPs, and albums", "cut", "/tracks/albums"),
+            [ReleaseMedium.Session] = new("Sessions", "Single-track live recordings", "session", "/tracks/sessions"),
+            [ReleaseMedium.Mix] = new("Mixes", "Single-track DJ mixes", "mix", "/tracks/mixes"),
+        };
+}