feature: Phase 22 SEO metadata component for public site

One presentational SeoHead renders the full OG/Twitter/JSON-LD head surface at prerender via typed schema.org builders. Per-medium release schema, config-sourced canonicals, 404 noindex. Zero CMS change.

DeepDrftPublic.Client/Pages/About.razor

@@ -2,8 +2,9 @@
 @using DeepDrftPublic.Client.Controls
 @implements IAsyncDisposable
 @inject IJSRuntime JsRuntime
+@inject SeoOptions Seo
 
-<PageTitle>The Collective - Deep DRFT</PageTitle>
+<SeoHead Model="@SeoModel.ForAbout(Seo)" />
 
 @* ──────────────────────────────────────────────────────────────────────────────
    THE LINER NOTES — a numbered three-movement editorial essay.

DeepDrftPublic.Client/Pages/AlbumsView.razor

@@ -1,7 +1,9 @@
 @page "/cuts"
+@using DeepDrftModels.Enums
 @using DeepDrftPublic.Client.Controls
+@inject SeoOptions Seo
 
-<PageTitle>DeepDrft Cuts</PageTitle>
+<SeoHead Model="@SeoModel.ForBrowse(Seo, ReleaseMedium.Cut, "/cuts")" />
 
 @* The shared release-card grid; each card routes to /cuts/{entryKey} via the one ReleaseRoutes table.
    Cuts show a track count where other media show the artist, supplied via SubtitleResolver. *@

DeepDrftPublic.Client/Pages/ArchiveView.razor

@@ -1,8 +1,9 @@
 @page "/archive"
 @using DeepDrftModels.Enums
 @using DeepDrftPublic.Client.Controls
+@inject SeoOptions Seo
 
-<PageTitle>DeepDrft Archive</PageTitle>
+<SeoHead Model="@SeoModel.ForBrowse(Seo, null, "/archive")" />
 
 <div>
     <MudContainer MaxWidth="MaxWidth.Large" Class="archive-view-container">

DeepDrftPublic.Client/Pages/CutDetail.razor

@@ -3,8 +3,7 @@
 @using DeepDrftPublic.Client.Controls
 @using DeepDrftPublic.Client.Services
 @inherits CutDetailBase
-
-<PageTitle>@(ViewModel.Release?.Title ?? "Cut") - DeepDrft</PageTitle>
+@inject SeoOptions Seo
 
 @if (ViewModel.IsLoading)
 {
@@ -37,6 +36,10 @@ else
     var hasYear = release.ReleaseDate is not null;
     var firstTrack = ViewModel.Tracks.Count > 0 ? ViewModel.Tracks[0] : null;
 
+    @* SEO head — fed from the same bridged release + ordered tracks, so the prerender and WASM passes
+       render identical tags (AC6). MusicAlbum/StudioAlbum with the ordered track list (§3.4). *@
+    <SeoHead Model="@SeoModel.ForRelease(Seo, release, ViewModel.Tracks)" />
+
     @* Full-screen content body (Phase 20 Wave 2 §1): the scaffold has no Class param, so a thin wrapper
        carries the min-height. dd-detail-fill keeps the body >= viewport height (below the nav) so the
        ambient visualizer reads full-screen and the site footer is pushed below the fold. *@

DeepDrftPublic.Client/Pages/Home.razor

@@ -1,8 +1,9 @@
 @page "/"
 @using DeepDrftPublic.Client.Controls
 @using DeepDrftPublic.Client.Services
+@inject SeoOptions Seo
 
-<PageTitle>Deep DRFT - Electronic Music Collective</PageTitle>
+<SeoHead Model="@SeoModel.ForHome(Seo)" />
 
 @* Hero - split 50/50 *@
 <section class="hero">

DeepDrftPublic.Client/Pages/MixDetail.razor

@@ -2,8 +2,7 @@
 @using DeepDrftPublic.Client.Controls
 @using DeepDrftPublic.Client.Services
 @inherits ReleaseDetailBase
-
-<PageTitle>@(ViewModel.Release?.Title ?? "Mix") - DeepDrft</PageTitle>
+@inject SeoOptions Seo
 
 @if (ViewModel.IsLoading)
 {
@@ -32,6 +31,11 @@ else if (ViewModel.NotFound || ViewModel.Release is null)
 else
 {
     var release = ViewModel.Release;
+    var mixTracks = ViewModel.Track is not null ? new[] { ViewModel.Track } : null;
+
+    @* SEO head — fed from the same bridged release + single track, so prerender and WASM render identical
+       tags (AC6). MusicRecording with ISO-8601 duration from the track (§3.4). *@
+    <SeoHead Model="@SeoModel.ForRelease(Seo, release, mixTracks)" />
 
     @* Full-page waveform sits behind the scaffold content. The scaffold's container is positioned
        above it via the mix-detail-foreground stacking context. TrackId lets the visualizer couple to

DeepDrftPublic.Client/Pages/MixesView.razor

@@ -1,8 +1,10 @@
 @page "/mixes"
+@using DeepDrftModels.Enums
 @using DeepDrftPublic.Client.Controls
 @inherits MediumBrowseBase
+@inject SeoOptions Seo
 
-<PageTitle>DeepDrft Mixes</PageTitle>
+<SeoHead Model="@SeoModel.ForBrowse(Seo, ReleaseMedium.Mix, "/mixes")" />
 
 <ReleaseGallery Releases="@Releases"
                 Loading="@Loading"

DeepDrftPublic.Client/Pages/NotFound.razor

@@ -1,4 +1,9 @@
 @page "/404"
+@using DeepDrftPublic.Client.Controls
+@inject SeoOptions Seo
+
+@* The 404 must not be indexed (AC8): noindex,follow — no canonical, no JSON-LD. *@
+<SeoHead Model="@SeoModel.ForNotFound(Seo)" />
 
 <MudText Typo="Typo.h3">
     Not Found

DeepDrftPublic.Client/Pages/SessionDetail.razor

@@ -3,8 +3,7 @@
 @using DeepDrftPublic.Client.Controls
 @using DeepDrftPublic.Client.Services
 @inherits ReleaseDetailBase
-
-<PageTitle>@(ViewModel.Release?.Title ?? "Session") - DeepDrft</PageTitle>
+@inject SeoOptions Seo
 
 @if (ViewModel.IsLoading)
 {
@@ -40,6 +39,10 @@ else
     // Hero image precedence: the session's dedicated hero, then the release cover, then a placeholder.
     var heroImage = !string.IsNullOrEmpty(heroKey) ? heroKey : release.ImagePath;
 
+    @* SEO head — fed from the same bridged release, so prerender and WASM render identical tags (AC6).
+       MusicAlbum/LiveAlbum (a session is a live release, §3.4/OQ6). *@
+    <SeoHead Model="@SeoModel.ForRelease(Seo, release)" />
+
     @* Ambient living waveform behind the hero overlay (Phase 12 §3e option b / §3f mode B). Session does
        NOT compose ReleaseDetailScaffold, so it mounts the shared engine directly with its own thin
        full-bleed wrapper — the engine is single-source either way, only the mount differs (§3b). The

DeepDrftPublic.Client/Pages/SessionsView.razor

@@ -1,8 +1,10 @@
 @page "/sessions"
+@using DeepDrftModels.Enums
 @using DeepDrftPublic.Client.Controls
 @inherits MediumBrowseBase
+@inject SeoOptions Seo
 
-<PageTitle>DeepDrft Sessions</PageTitle>
+<SeoHead Model="@SeoModel.ForBrowse(Seo, ReleaseMedium.Session, "/sessions")" />
 
 <ReleaseGallery Releases="@Releases"
                 Loading="@Loading"