Phase 9 Wave 2: api/release endpoint family — medium-aware reads + metadata writes

Adds ReleaseRepository/ReleaseManager (IReleaseService) for paged medium-filtered
release reads and Session/Mix satellite writes, UnifiedReleaseService orchestrating
vault+SQL, and ReleaseController (5 endpoints). Refactors WaveformProfileService for
configurable bucketCount/vaultName (backward-compatible) and adds the mix-waveforms vault.
Promotes brittle error-string literals to named constants (MixHasNoTrackMessage,
MixTrackNoAudioMessage) on UnifiedReleaseService.

DeepDrftAPI/Program.cs

@@ -64,6 +64,14 @@ builder.Services
     .AddScoped<ITrackService>(sp => sp.GetRequiredService<TrackManager>());
 builder.Services.AddScoped<UnifiedTrackService>();
 
+// Release domain — medium-aware read projection + satellite metadata writes. ReleaseManager is the
+// IReleaseService implementation; UnifiedReleaseService orchestrates the vault + SQL satellite writes.
+builder.Services
+    .AddScoped<ReleaseRepository>()
+    .AddScoped<ReleaseManager>()
+    .AddScoped<IReleaseService>(sp => sp.GetRequiredService<ReleaseManager>());
+builder.Services.AddScoped<UnifiedReleaseService>();
+
 // AuthBlocks: JWT Bearer auth, Identity, EF schema, role + admin seeding. This API host owns the
 // AuthBlocks API surface (registration, migration/seed, endpoint mounting). The Manager keeps only
 // web-side auth (AuthBlocksWeb) and never holds the signing secret, email creds, or admin creds.