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/ICmsReleaseService.cs

@@ -0,0 +1,51 @@
+using DeepDrftModels.DTOs;
+using DeepDrftModels.Enums;
+using Models.Common;
+using NetBlocks.Models;
+
+namespace DeepDrftManager.Services;
+
+/// <summary>
+/// CMS-side release operations for the Manager host. Mirrors <see cref="ICmsTrackService"/>: every
+/// read and write goes over HTTP to DeepDrftAPI's <c>api/release</c> family, which is the single
+/// authority over both the SQL metadata store and the binary vault. The Manager holds no in-process
+/// data layer.
+/// </summary>
+public interface ICmsReleaseService
+{
+    /// <summary>
+    /// Fetch a page of releases from <c>GET api/release</c>, optionally filtered to one
+    /// <paramref name="medium"/>. The matching medium's metadata satellite is populated on each row;
+    /// the others are null. Null medium returns all releases unfiltered.
+    /// </summary>
+    Task<ResultContainer<PagedResult<ReleaseDto>>> GetPagedAsync(
+        ReleaseMedium? medium,
+        int page, int pageSize, string? sortColumn, bool sortDescending,
+        CancellationToken ct = default);
+
+    /// <summary>
+    /// Fetch a single release with both metadata navs from <c>GET api/release/{id}</c> (nulls for the
+    /// non-matching medium). A 404 returns a passing result with a null value.
+    /// </summary>
+    Task<ResultContainer<ReleaseDto?>> GetByIdAsync(long id, CancellationToken ct = default);
+
+    /// <summary>
+    /// Upload a Session hero image via <c>POST api/release/{id}/session/hero-image</c> (multipart).
+    /// The server stores it in the image vault and sets <c>SessionMetadata.HeroImageEntryKey</c>.
+    /// Maps a 404 to a "Release not found." failure; relays 4xx validation text as-is.
+    /// </summary>
+    Task<Result> UploadSessionHeroImageAsync(
+        long releaseId,
+        Stream imageStream,
+        string fileName,
+        string contentType,
+        CancellationToken ct = default);
+
+    /// <summary>
+    /// Trigger high-resolution waveform generation for a Mix via
+    /// <c>POST api/release/{id}/mix/waveform</c> (no body). The server fetches the mix audio from its
+    /// own vault, computes the datum, stores it, and sets <c>MixMetadata.WaveformEntryKey</c>. Maps a
+    /// 404 to a "Mix audio not found." failure.
+    /// </summary>
+    Task<Result> GenerateMixWaveformAsync(long releaseId, CancellationToken ct = default);
+}