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/Services/CmsTrackBrowserViewModel.cs

@@ -2,11 +2,12 @@ using DeepDrftModels.DTOs;
 
 namespace DeepDrftManager.Services;
 
-/// <summary>The three browse dimensions for the /tracks page.</summary>
+/// <summary>The browse dimensions for the /tracks page.</summary>
 public enum BrowseMode
 {
     Tracks,
     Albums,
+    Archive,
     Genres,
 }