feat: sync status indicator, unsubscribe queue UI, email body preview

SyncStatus widget polls /sync/status and shows a live progress bar in
the topbar while syncing, or last-synced time / error otherwise.

Unsubscribe page reworked into a proper queue: status filter tabs
(All/Pending/Succeeded/Failed), select-all, sorted by volume, status
badges, and a result toast after processing.

GET /email/{id} returns full BodyText; Senders detail view fetches
and renders it instead of just the snippet.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/InboxIntel.Api/Controllers/EmailController.cs

@@ -27,6 +27,21 @@ public class EmailController : ApiControllerBase
         _db = db;
     }
 
+    /// <summary>Full email detail including body text, for the inline detail view.</summary>
+    [HttpGet("{id:guid}")]
+    public async Task<IActionResult> Get(Guid id, CancellationToken ct)
+    {
+        var e = await _db.Emails
+            .Where(e => e.Id == id && e.UserId == UserId)
+            .Select(e => new EmailDetailDto(
+                e.Id, e.GmailMessageId, e.Subject, e.Snippet, e.BodyText,
+                e.Sender!.Address, e.Sender.DisplayName, e.SentAtUtc,
+                e.IsUnread, e.IsStarred, e.HasAttachments, e.SizeEstimateBytes,
+                e.Category, e.HasListUnsubscribe, e.SupportsOneClickUnsubscribe))
+            .FirstOrDefaultAsync(ct);
+        return e is null ? NotFound() : Ok(e);
+    }
+
     [HttpPost("{id:guid}/read")]
     public Task<IActionResult> MarkRead(Guid id, CancellationToken ct) => Act(id, CleanupActionType.MarkRead, ct);